Annotation of embedaddon/sqlite3/src/select.c, revision 1.1
1.1 ! misho 1: /*
! 2: ** 2001 September 15
! 3: **
! 4: ** The author disclaims copyright to this source code. In place of
! 5: ** a legal notice, here is a blessing:
! 6: **
! 7: ** May you do good and not evil.
! 8: ** May you find forgiveness for yourself and forgive others.
! 9: ** May you share freely, never taking more than you give.
! 10: **
! 11: *************************************************************************
! 12: ** This file contains C code routines that are called by the parser
! 13: ** to handle SELECT statements in SQLite.
! 14: */
! 15: #include "sqliteInt.h"
! 16:
! 17:
! 18: /*
! 19: ** Delete all the content of a Select structure but do not deallocate
! 20: ** the select structure itself.
! 21: */
! 22: static void clearSelect(sqlite3 *db, Select *p){
! 23: sqlite3ExprListDelete(db, p->pEList);
! 24: sqlite3SrcListDelete(db, p->pSrc);
! 25: sqlite3ExprDelete(db, p->pWhere);
! 26: sqlite3ExprListDelete(db, p->pGroupBy);
! 27: sqlite3ExprDelete(db, p->pHaving);
! 28: sqlite3ExprListDelete(db, p->pOrderBy);
! 29: sqlite3SelectDelete(db, p->pPrior);
! 30: sqlite3ExprDelete(db, p->pLimit);
! 31: sqlite3ExprDelete(db, p->pOffset);
! 32: }
! 33:
! 34: /*
! 35: ** Initialize a SelectDest structure.
! 36: */
! 37: void sqlite3SelectDestInit(SelectDest *pDest, int eDest, int iParm){
! 38: pDest->eDest = (u8)eDest;
! 39: pDest->iParm = iParm;
! 40: pDest->affinity = 0;
! 41: pDest->iMem = 0;
! 42: pDest->nMem = 0;
! 43: }
! 44:
! 45:
! 46: /*
! 47: ** Allocate a new Select structure and return a pointer to that
! 48: ** structure.
! 49: */
! 50: Select *sqlite3SelectNew(
! 51: Parse *pParse, /* Parsing context */
! 52: ExprList *pEList, /* which columns to include in the result */
! 53: SrcList *pSrc, /* the FROM clause -- which tables to scan */
! 54: Expr *pWhere, /* the WHERE clause */
! 55: ExprList *pGroupBy, /* the GROUP BY clause */
! 56: Expr *pHaving, /* the HAVING clause */
! 57: ExprList *pOrderBy, /* the ORDER BY clause */
! 58: int isDistinct, /* true if the DISTINCT keyword is present */
! 59: Expr *pLimit, /* LIMIT value. NULL means not used */
! 60: Expr *pOffset /* OFFSET value. NULL means no offset */
! 61: ){
! 62: Select *pNew;
! 63: Select standin;
! 64: sqlite3 *db = pParse->db;
! 65: pNew = sqlite3DbMallocZero(db, sizeof(*pNew) );
! 66: assert( db->mallocFailed || !pOffset || pLimit ); /* OFFSET implies LIMIT */
! 67: if( pNew==0 ){
! 68: assert( db->mallocFailed );
! 69: pNew = &standin;
! 70: memset(pNew, 0, sizeof(*pNew));
! 71: }
! 72: if( pEList==0 ){
! 73: pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db,TK_ALL,0));
! 74: }
! 75: pNew->pEList = pEList;
! 76: pNew->pSrc = pSrc;
! 77: pNew->pWhere = pWhere;
! 78: pNew->pGroupBy = pGroupBy;
! 79: pNew->pHaving = pHaving;
! 80: pNew->pOrderBy = pOrderBy;
! 81: pNew->selFlags = isDistinct ? SF_Distinct : 0;
! 82: pNew->op = TK_SELECT;
! 83: pNew->pLimit = pLimit;
! 84: pNew->pOffset = pOffset;
! 85: assert( pOffset==0 || pLimit!=0 );
! 86: pNew->addrOpenEphm[0] = -1;
! 87: pNew->addrOpenEphm[1] = -1;
! 88: pNew->addrOpenEphm[2] = -1;
! 89: if( db->mallocFailed ) {
! 90: clearSelect(db, pNew);
! 91: if( pNew!=&standin ) sqlite3DbFree(db, pNew);
! 92: pNew = 0;
! 93: }else{
! 94: assert( pNew->pSrc!=0 || pParse->nErr>0 );
! 95: }
! 96: assert( pNew!=&standin );
! 97: return pNew;
! 98: }
! 99:
! 100: /*
! 101: ** Delete the given Select structure and all of its substructures.
! 102: */
! 103: void sqlite3SelectDelete(sqlite3 *db, Select *p){
! 104: if( p ){
! 105: clearSelect(db, p);
! 106: sqlite3DbFree(db, p);
! 107: }
! 108: }
! 109:
! 110: /*
! 111: ** Given 1 to 3 identifiers preceeding the JOIN keyword, determine the
! 112: ** type of join. Return an integer constant that expresses that type
! 113: ** in terms of the following bit values:
! 114: **
! 115: ** JT_INNER
! 116: ** JT_CROSS
! 117: ** JT_OUTER
! 118: ** JT_NATURAL
! 119: ** JT_LEFT
! 120: ** JT_RIGHT
! 121: **
! 122: ** A full outer join is the combination of JT_LEFT and JT_RIGHT.
! 123: **
! 124: ** If an illegal or unsupported join type is seen, then still return
! 125: ** a join type, but put an error in the pParse structure.
! 126: */
! 127: int sqlite3JoinType(Parse *pParse, Token *pA, Token *pB, Token *pC){
! 128: int jointype = 0;
! 129: Token *apAll[3];
! 130: Token *p;
! 131: /* 0123456789 123456789 123456789 123 */
! 132: static const char zKeyText[] = "naturaleftouterightfullinnercross";
! 133: static const struct {
! 134: u8 i; /* Beginning of keyword text in zKeyText[] */
! 135: u8 nChar; /* Length of the keyword in characters */
! 136: u8 code; /* Join type mask */
! 137: } aKeyword[] = {
! 138: /* natural */ { 0, 7, JT_NATURAL },
! 139: /* left */ { 6, 4, JT_LEFT|JT_OUTER },
! 140: /* outer */ { 10, 5, JT_OUTER },
! 141: /* right */ { 14, 5, JT_RIGHT|JT_OUTER },
! 142: /* full */ { 19, 4, JT_LEFT|JT_RIGHT|JT_OUTER },
! 143: /* inner */ { 23, 5, JT_INNER },
! 144: /* cross */ { 28, 5, JT_INNER|JT_CROSS },
! 145: };
! 146: int i, j;
! 147: apAll[0] = pA;
! 148: apAll[1] = pB;
! 149: apAll[2] = pC;
! 150: for(i=0; i<3 && apAll[i]; i++){
! 151: p = apAll[i];
! 152: for(j=0; j<ArraySize(aKeyword); j++){
! 153: if( p->n==aKeyword[j].nChar
! 154: && sqlite3StrNICmp((char*)p->z, &zKeyText[aKeyword[j].i], p->n)==0 ){
! 155: jointype |= aKeyword[j].code;
! 156: break;
! 157: }
! 158: }
! 159: testcase( j==0 || j==1 || j==2 || j==3 || j==4 || j==5 || j==6 );
! 160: if( j>=ArraySize(aKeyword) ){
! 161: jointype |= JT_ERROR;
! 162: break;
! 163: }
! 164: }
! 165: if(
! 166: (jointype & (JT_INNER|JT_OUTER))==(JT_INNER|JT_OUTER) ||
! 167: (jointype & JT_ERROR)!=0
! 168: ){
! 169: const char *zSp = " ";
! 170: assert( pB!=0 );
! 171: if( pC==0 ){ zSp++; }
! 172: sqlite3ErrorMsg(pParse, "unknown or unsupported join type: "
! 173: "%T %T%s%T", pA, pB, zSp, pC);
! 174: jointype = JT_INNER;
! 175: }else if( (jointype & JT_OUTER)!=0
! 176: && (jointype & (JT_LEFT|JT_RIGHT))!=JT_LEFT ){
! 177: sqlite3ErrorMsg(pParse,
! 178: "RIGHT and FULL OUTER JOINs are not currently supported");
! 179: jointype = JT_INNER;
! 180: }
! 181: return jointype;
! 182: }
! 183:
! 184: /*
! 185: ** Return the index of a column in a table. Return -1 if the column
! 186: ** is not contained in the table.
! 187: */
! 188: static int columnIndex(Table *pTab, const char *zCol){
! 189: int i;
! 190: for(i=0; i<pTab->nCol; i++){
! 191: if( sqlite3StrICmp(pTab->aCol[i].zName, zCol)==0 ) return i;
! 192: }
! 193: return -1;
! 194: }
! 195:
! 196: /*
! 197: ** Search the first N tables in pSrc, from left to right, looking for a
! 198: ** table that has a column named zCol.
! 199: **
! 200: ** When found, set *piTab and *piCol to the table index and column index
! 201: ** of the matching column and return TRUE.
! 202: **
! 203: ** If not found, return FALSE.
! 204: */
! 205: static int tableAndColumnIndex(
! 206: SrcList *pSrc, /* Array of tables to search */
! 207: int N, /* Number of tables in pSrc->a[] to search */
! 208: const char *zCol, /* Name of the column we are looking for */
! 209: int *piTab, /* Write index of pSrc->a[] here */
! 210: int *piCol /* Write index of pSrc->a[*piTab].pTab->aCol[] here */
! 211: ){
! 212: int i; /* For looping over tables in pSrc */
! 213: int iCol; /* Index of column matching zCol */
! 214:
! 215: assert( (piTab==0)==(piCol==0) ); /* Both or neither are NULL */
! 216: for(i=0; i<N; i++){
! 217: iCol = columnIndex(pSrc->a[i].pTab, zCol);
! 218: if( iCol>=0 ){
! 219: if( piTab ){
! 220: *piTab = i;
! 221: *piCol = iCol;
! 222: }
! 223: return 1;
! 224: }
! 225: }
! 226: return 0;
! 227: }
! 228:
! 229: /*
! 230: ** This function is used to add terms implied by JOIN syntax to the
! 231: ** WHERE clause expression of a SELECT statement. The new term, which
! 232: ** is ANDed with the existing WHERE clause, is of the form:
! 233: **
! 234: ** (tab1.col1 = tab2.col2)
! 235: **
! 236: ** where tab1 is the iSrc'th table in SrcList pSrc and tab2 is the
! 237: ** (iSrc+1)'th. Column col1 is column iColLeft of tab1, and col2 is
! 238: ** column iColRight of tab2.
! 239: */
! 240: static void addWhereTerm(
! 241: Parse *pParse, /* Parsing context */
! 242: SrcList *pSrc, /* List of tables in FROM clause */
! 243: int iLeft, /* Index of first table to join in pSrc */
! 244: int iColLeft, /* Index of column in first table */
! 245: int iRight, /* Index of second table in pSrc */
! 246: int iColRight, /* Index of column in second table */
! 247: int isOuterJoin, /* True if this is an OUTER join */
! 248: Expr **ppWhere /* IN/OUT: The WHERE clause to add to */
! 249: ){
! 250: sqlite3 *db = pParse->db;
! 251: Expr *pE1;
! 252: Expr *pE2;
! 253: Expr *pEq;
! 254:
! 255: assert( iLeft<iRight );
! 256: assert( pSrc->nSrc>iRight );
! 257: assert( pSrc->a[iLeft].pTab );
! 258: assert( pSrc->a[iRight].pTab );
! 259:
! 260: pE1 = sqlite3CreateColumnExpr(db, pSrc, iLeft, iColLeft);
! 261: pE2 = sqlite3CreateColumnExpr(db, pSrc, iRight, iColRight);
! 262:
! 263: pEq = sqlite3PExpr(pParse, TK_EQ, pE1, pE2, 0);
! 264: if( pEq && isOuterJoin ){
! 265: ExprSetProperty(pEq, EP_FromJoin);
! 266: assert( !ExprHasAnyProperty(pEq, EP_TokenOnly|EP_Reduced) );
! 267: ExprSetIrreducible(pEq);
! 268: pEq->iRightJoinTable = (i16)pE2->iTable;
! 269: }
! 270: *ppWhere = sqlite3ExprAnd(db, *ppWhere, pEq);
! 271: }
! 272:
! 273: /*
! 274: ** Set the EP_FromJoin property on all terms of the given expression.
! 275: ** And set the Expr.iRightJoinTable to iTable for every term in the
! 276: ** expression.
! 277: **
! 278: ** The EP_FromJoin property is used on terms of an expression to tell
! 279: ** the LEFT OUTER JOIN processing logic that this term is part of the
! 280: ** join restriction specified in the ON or USING clause and not a part
! 281: ** of the more general WHERE clause. These terms are moved over to the
! 282: ** WHERE clause during join processing but we need to remember that they
! 283: ** originated in the ON or USING clause.
! 284: **
! 285: ** The Expr.iRightJoinTable tells the WHERE clause processing that the
! 286: ** expression depends on table iRightJoinTable even if that table is not
! 287: ** explicitly mentioned in the expression. That information is needed
! 288: ** for cases like this:
! 289: **
! 290: ** SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.b AND t1.x=5
! 291: **
! 292: ** The where clause needs to defer the handling of the t1.x=5
! 293: ** term until after the t2 loop of the join. In that way, a
! 294: ** NULL t2 row will be inserted whenever t1.x!=5. If we do not
! 295: ** defer the handling of t1.x=5, it will be processed immediately
! 296: ** after the t1 loop and rows with t1.x!=5 will never appear in
! 297: ** the output, which is incorrect.
! 298: */
! 299: static void setJoinExpr(Expr *p, int iTable){
! 300: while( p ){
! 301: ExprSetProperty(p, EP_FromJoin);
! 302: assert( !ExprHasAnyProperty(p, EP_TokenOnly|EP_Reduced) );
! 303: ExprSetIrreducible(p);
! 304: p->iRightJoinTable = (i16)iTable;
! 305: setJoinExpr(p->pLeft, iTable);
! 306: p = p->pRight;
! 307: }
! 308: }
! 309:
! 310: /*
! 311: ** This routine processes the join information for a SELECT statement.
! 312: ** ON and USING clauses are converted into extra terms of the WHERE clause.
! 313: ** NATURAL joins also create extra WHERE clause terms.
! 314: **
! 315: ** The terms of a FROM clause are contained in the Select.pSrc structure.
! 316: ** The left most table is the first entry in Select.pSrc. The right-most
! 317: ** table is the last entry. The join operator is held in the entry to
! 318: ** the left. Thus entry 0 contains the join operator for the join between
! 319: ** entries 0 and 1. Any ON or USING clauses associated with the join are
! 320: ** also attached to the left entry.
! 321: **
! 322: ** This routine returns the number of errors encountered.
! 323: */
! 324: static int sqliteProcessJoin(Parse *pParse, Select *p){
! 325: SrcList *pSrc; /* All tables in the FROM clause */
! 326: int i, j; /* Loop counters */
! 327: struct SrcList_item *pLeft; /* Left table being joined */
! 328: struct SrcList_item *pRight; /* Right table being joined */
! 329:
! 330: pSrc = p->pSrc;
! 331: pLeft = &pSrc->a[0];
! 332: pRight = &pLeft[1];
! 333: for(i=0; i<pSrc->nSrc-1; i++, pRight++, pLeft++){
! 334: Table *pLeftTab = pLeft->pTab;
! 335: Table *pRightTab = pRight->pTab;
! 336: int isOuter;
! 337:
! 338: if( NEVER(pLeftTab==0 || pRightTab==0) ) continue;
! 339: isOuter = (pRight->jointype & JT_OUTER)!=0;
! 340:
! 341: /* When the NATURAL keyword is present, add WHERE clause terms for
! 342: ** every column that the two tables have in common.
! 343: */
! 344: if( pRight->jointype & JT_NATURAL ){
! 345: if( pRight->pOn || pRight->pUsing ){
! 346: sqlite3ErrorMsg(pParse, "a NATURAL join may not have "
! 347: "an ON or USING clause", 0);
! 348: return 1;
! 349: }
! 350: for(j=0; j<pRightTab->nCol; j++){
! 351: char *zName; /* Name of column in the right table */
! 352: int iLeft; /* Matching left table */
! 353: int iLeftCol; /* Matching column in the left table */
! 354:
! 355: zName = pRightTab->aCol[j].zName;
! 356: if( tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol) ){
! 357: addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, j,
! 358: isOuter, &p->pWhere);
! 359: }
! 360: }
! 361: }
! 362:
! 363: /* Disallow both ON and USING clauses in the same join
! 364: */
! 365: if( pRight->pOn && pRight->pUsing ){
! 366: sqlite3ErrorMsg(pParse, "cannot have both ON and USING "
! 367: "clauses in the same join");
! 368: return 1;
! 369: }
! 370:
! 371: /* Add the ON clause to the end of the WHERE clause, connected by
! 372: ** an AND operator.
! 373: */
! 374: if( pRight->pOn ){
! 375: if( isOuter ) setJoinExpr(pRight->pOn, pRight->iCursor);
! 376: p->pWhere = sqlite3ExprAnd(pParse->db, p->pWhere, pRight->pOn);
! 377: pRight->pOn = 0;
! 378: }
! 379:
! 380: /* Create extra terms on the WHERE clause for each column named
! 381: ** in the USING clause. Example: If the two tables to be joined are
! 382: ** A and B and the USING clause names X, Y, and Z, then add this
! 383: ** to the WHERE clause: A.X=B.X AND A.Y=B.Y AND A.Z=B.Z
! 384: ** Report an error if any column mentioned in the USING clause is
! 385: ** not contained in both tables to be joined.
! 386: */
! 387: if( pRight->pUsing ){
! 388: IdList *pList = pRight->pUsing;
! 389: for(j=0; j<pList->nId; j++){
! 390: char *zName; /* Name of the term in the USING clause */
! 391: int iLeft; /* Table on the left with matching column name */
! 392: int iLeftCol; /* Column number of matching column on the left */
! 393: int iRightCol; /* Column number of matching column on the right */
! 394:
! 395: zName = pList->a[j].zName;
! 396: iRightCol = columnIndex(pRightTab, zName);
! 397: if( iRightCol<0
! 398: || !tableAndColumnIndex(pSrc, i+1, zName, &iLeft, &iLeftCol)
! 399: ){
! 400: sqlite3ErrorMsg(pParse, "cannot join using column %s - column "
! 401: "not present in both tables", zName);
! 402: return 1;
! 403: }
! 404: addWhereTerm(pParse, pSrc, iLeft, iLeftCol, i+1, iRightCol,
! 405: isOuter, &p->pWhere);
! 406: }
! 407: }
! 408: }
! 409: return 0;
! 410: }
! 411:
! 412: /*
! 413: ** Insert code into "v" that will push the record on the top of the
! 414: ** stack into the sorter.
! 415: */
! 416: static void pushOntoSorter(
! 417: Parse *pParse, /* Parser context */
! 418: ExprList *pOrderBy, /* The ORDER BY clause */
! 419: Select *pSelect, /* The whole SELECT statement */
! 420: int regData /* Register holding data to be sorted */
! 421: ){
! 422: Vdbe *v = pParse->pVdbe;
! 423: int nExpr = pOrderBy->nExpr;
! 424: int regBase = sqlite3GetTempRange(pParse, nExpr+2);
! 425: int regRecord = sqlite3GetTempReg(pParse);
! 426: int op;
! 427: sqlite3ExprCacheClear(pParse);
! 428: sqlite3ExprCodeExprList(pParse, pOrderBy, regBase, 0);
! 429: sqlite3VdbeAddOp2(v, OP_Sequence, pOrderBy->iECursor, regBase+nExpr);
! 430: sqlite3ExprCodeMove(pParse, regData, regBase+nExpr+1, 1);
! 431: sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nExpr + 2, regRecord);
! 432: if( pSelect->selFlags & SF_UseSorter ){
! 433: op = OP_SorterInsert;
! 434: }else{
! 435: op = OP_IdxInsert;
! 436: }
! 437: sqlite3VdbeAddOp2(v, op, pOrderBy->iECursor, regRecord);
! 438: sqlite3ReleaseTempReg(pParse, regRecord);
! 439: sqlite3ReleaseTempRange(pParse, regBase, nExpr+2);
! 440: if( pSelect->iLimit ){
! 441: int addr1, addr2;
! 442: int iLimit;
! 443: if( pSelect->iOffset ){
! 444: iLimit = pSelect->iOffset+1;
! 445: }else{
! 446: iLimit = pSelect->iLimit;
! 447: }
! 448: addr1 = sqlite3VdbeAddOp1(v, OP_IfZero, iLimit);
! 449: sqlite3VdbeAddOp2(v, OP_AddImm, iLimit, -1);
! 450: addr2 = sqlite3VdbeAddOp0(v, OP_Goto);
! 451: sqlite3VdbeJumpHere(v, addr1);
! 452: sqlite3VdbeAddOp1(v, OP_Last, pOrderBy->iECursor);
! 453: sqlite3VdbeAddOp1(v, OP_Delete, pOrderBy->iECursor);
! 454: sqlite3VdbeJumpHere(v, addr2);
! 455: }
! 456: }
! 457:
! 458: /*
! 459: ** Add code to implement the OFFSET
! 460: */
! 461: static void codeOffset(
! 462: Vdbe *v, /* Generate code into this VM */
! 463: Select *p, /* The SELECT statement being coded */
! 464: int iContinue /* Jump here to skip the current record */
! 465: ){
! 466: if( p->iOffset && iContinue!=0 ){
! 467: int addr;
! 468: sqlite3VdbeAddOp2(v, OP_AddImm, p->iOffset, -1);
! 469: addr = sqlite3VdbeAddOp1(v, OP_IfNeg, p->iOffset);
! 470: sqlite3VdbeAddOp2(v, OP_Goto, 0, iContinue);
! 471: VdbeComment((v, "skip OFFSET records"));
! 472: sqlite3VdbeJumpHere(v, addr);
! 473: }
! 474: }
! 475:
! 476: /*
! 477: ** Add code that will check to make sure the N registers starting at iMem
! 478: ** form a distinct entry. iTab is a sorting index that holds previously
! 479: ** seen combinations of the N values. A new entry is made in iTab
! 480: ** if the current N values are new.
! 481: **
! 482: ** A jump to addrRepeat is made and the N+1 values are popped from the
! 483: ** stack if the top N elements are not distinct.
! 484: */
! 485: static void codeDistinct(
! 486: Parse *pParse, /* Parsing and code generating context */
! 487: int iTab, /* A sorting index used to test for distinctness */
! 488: int addrRepeat, /* Jump to here if not distinct */
! 489: int N, /* Number of elements */
! 490: int iMem /* First element */
! 491: ){
! 492: Vdbe *v;
! 493: int r1;
! 494:
! 495: v = pParse->pVdbe;
! 496: r1 = sqlite3GetTempReg(pParse);
! 497: sqlite3VdbeAddOp4Int(v, OP_Found, iTab, addrRepeat, iMem, N);
! 498: sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, N, r1);
! 499: sqlite3VdbeAddOp2(v, OP_IdxInsert, iTab, r1);
! 500: sqlite3ReleaseTempReg(pParse, r1);
! 501: }
! 502:
! 503: #ifndef SQLITE_OMIT_SUBQUERY
! 504: /*
! 505: ** Generate an error message when a SELECT is used within a subexpression
! 506: ** (example: "a IN (SELECT * FROM table)") but it has more than 1 result
! 507: ** column. We do this in a subroutine because the error used to occur
! 508: ** in multiple places. (The error only occurs in one place now, but we
! 509: ** retain the subroutine to minimize code disruption.)
! 510: */
! 511: static int checkForMultiColumnSelectError(
! 512: Parse *pParse, /* Parse context. */
! 513: SelectDest *pDest, /* Destination of SELECT results */
! 514: int nExpr /* Number of result columns returned by SELECT */
! 515: ){
! 516: int eDest = pDest->eDest;
! 517: if( nExpr>1 && (eDest==SRT_Mem || eDest==SRT_Set) ){
! 518: sqlite3ErrorMsg(pParse, "only a single result allowed for "
! 519: "a SELECT that is part of an expression");
! 520: return 1;
! 521: }else{
! 522: return 0;
! 523: }
! 524: }
! 525: #endif
! 526:
! 527: /*
! 528: ** This routine generates the code for the inside of the inner loop
! 529: ** of a SELECT.
! 530: **
! 531: ** If srcTab and nColumn are both zero, then the pEList expressions
! 532: ** are evaluated in order to get the data for this row. If nColumn>0
! 533: ** then data is pulled from srcTab and pEList is used only to get the
! 534: ** datatypes for each column.
! 535: */
! 536: static void selectInnerLoop(
! 537: Parse *pParse, /* The parser context */
! 538: Select *p, /* The complete select statement being coded */
! 539: ExprList *pEList, /* List of values being extracted */
! 540: int srcTab, /* Pull data from this table */
! 541: int nColumn, /* Number of columns in the source table */
! 542: ExprList *pOrderBy, /* If not NULL, sort results using this key */
! 543: int distinct, /* If >=0, make sure results are distinct */
! 544: SelectDest *pDest, /* How to dispose of the results */
! 545: int iContinue, /* Jump here to continue with next row */
! 546: int iBreak /* Jump here to break out of the inner loop */
! 547: ){
! 548: Vdbe *v = pParse->pVdbe;
! 549: int i;
! 550: int hasDistinct; /* True if the DISTINCT keyword is present */
! 551: int regResult; /* Start of memory holding result set */
! 552: int eDest = pDest->eDest; /* How to dispose of results */
! 553: int iParm = pDest->iParm; /* First argument to disposal method */
! 554: int nResultCol; /* Number of result columns */
! 555:
! 556: assert( v );
! 557: if( NEVER(v==0) ) return;
! 558: assert( pEList!=0 );
! 559: hasDistinct = distinct>=0;
! 560: if( pOrderBy==0 && !hasDistinct ){
! 561: codeOffset(v, p, iContinue);
! 562: }
! 563:
! 564: /* Pull the requested columns.
! 565: */
! 566: if( nColumn>0 ){
! 567: nResultCol = nColumn;
! 568: }else{
! 569: nResultCol = pEList->nExpr;
! 570: }
! 571: if( pDest->iMem==0 ){
! 572: pDest->iMem = pParse->nMem+1;
! 573: pDest->nMem = nResultCol;
! 574: pParse->nMem += nResultCol;
! 575: }else{
! 576: assert( pDest->nMem==nResultCol );
! 577: }
! 578: regResult = pDest->iMem;
! 579: if( nColumn>0 ){
! 580: for(i=0; i<nColumn; i++){
! 581: sqlite3VdbeAddOp3(v, OP_Column, srcTab, i, regResult+i);
! 582: }
! 583: }else if( eDest!=SRT_Exists ){
! 584: /* If the destination is an EXISTS(...) expression, the actual
! 585: ** values returned by the SELECT are not required.
! 586: */
! 587: sqlite3ExprCacheClear(pParse);
! 588: sqlite3ExprCodeExprList(pParse, pEList, regResult, eDest==SRT_Output);
! 589: }
! 590: nColumn = nResultCol;
! 591:
! 592: /* If the DISTINCT keyword was present on the SELECT statement
! 593: ** and this row has been seen before, then do not make this row
! 594: ** part of the result.
! 595: */
! 596: if( hasDistinct ){
! 597: assert( pEList!=0 );
! 598: assert( pEList->nExpr==nColumn );
! 599: codeDistinct(pParse, distinct, iContinue, nColumn, regResult);
! 600: if( pOrderBy==0 ){
! 601: codeOffset(v, p, iContinue);
! 602: }
! 603: }
! 604:
! 605: switch( eDest ){
! 606: /* In this mode, write each query result to the key of the temporary
! 607: ** table iParm.
! 608: */
! 609: #ifndef SQLITE_OMIT_COMPOUND_SELECT
! 610: case SRT_Union: {
! 611: int r1;
! 612: r1 = sqlite3GetTempReg(pParse);
! 613: sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
! 614: sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
! 615: sqlite3ReleaseTempReg(pParse, r1);
! 616: break;
! 617: }
! 618:
! 619: /* Construct a record from the query result, but instead of
! 620: ** saving that record, use it as a key to delete elements from
! 621: ** the temporary table iParm.
! 622: */
! 623: case SRT_Except: {
! 624: sqlite3VdbeAddOp3(v, OP_IdxDelete, iParm, regResult, nColumn);
! 625: break;
! 626: }
! 627: #endif
! 628:
! 629: /* Store the result as data using a unique key.
! 630: */
! 631: case SRT_Table:
! 632: case SRT_EphemTab: {
! 633: int r1 = sqlite3GetTempReg(pParse);
! 634: testcase( eDest==SRT_Table );
! 635: testcase( eDest==SRT_EphemTab );
! 636: sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
! 637: if( pOrderBy ){
! 638: pushOntoSorter(pParse, pOrderBy, p, r1);
! 639: }else{
! 640: int r2 = sqlite3GetTempReg(pParse);
! 641: sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, r2);
! 642: sqlite3VdbeAddOp3(v, OP_Insert, iParm, r1, r2);
! 643: sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
! 644: sqlite3ReleaseTempReg(pParse, r2);
! 645: }
! 646: sqlite3ReleaseTempReg(pParse, r1);
! 647: break;
! 648: }
! 649:
! 650: #ifndef SQLITE_OMIT_SUBQUERY
! 651: /* If we are creating a set for an "expr IN (SELECT ...)" construct,
! 652: ** then there should be a single item on the stack. Write this
! 653: ** item into the set table with bogus data.
! 654: */
! 655: case SRT_Set: {
! 656: assert( nColumn==1 );
! 657: p->affinity = sqlite3CompareAffinity(pEList->a[0].pExpr, pDest->affinity);
! 658: if( pOrderBy ){
! 659: /* At first glance you would think we could optimize out the
! 660: ** ORDER BY in this case since the order of entries in the set
! 661: ** does not matter. But there might be a LIMIT clause, in which
! 662: ** case the order does matter */
! 663: pushOntoSorter(pParse, pOrderBy, p, regResult);
! 664: }else{
! 665: int r1 = sqlite3GetTempReg(pParse);
! 666: sqlite3VdbeAddOp4(v, OP_MakeRecord, regResult, 1, r1, &p->affinity, 1);
! 667: sqlite3ExprCacheAffinityChange(pParse, regResult, 1);
! 668: sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, r1);
! 669: sqlite3ReleaseTempReg(pParse, r1);
! 670: }
! 671: break;
! 672: }
! 673:
! 674: /* If any row exist in the result set, record that fact and abort.
! 675: */
! 676: case SRT_Exists: {
! 677: sqlite3VdbeAddOp2(v, OP_Integer, 1, iParm);
! 678: /* The LIMIT clause will terminate the loop for us */
! 679: break;
! 680: }
! 681:
! 682: /* If this is a scalar select that is part of an expression, then
! 683: ** store the results in the appropriate memory cell and break out
! 684: ** of the scan loop.
! 685: */
! 686: case SRT_Mem: {
! 687: assert( nColumn==1 );
! 688: if( pOrderBy ){
! 689: pushOntoSorter(pParse, pOrderBy, p, regResult);
! 690: }else{
! 691: sqlite3ExprCodeMove(pParse, regResult, iParm, 1);
! 692: /* The LIMIT clause will jump out of the loop for us */
! 693: }
! 694: break;
! 695: }
! 696: #endif /* #ifndef SQLITE_OMIT_SUBQUERY */
! 697:
! 698: /* Send the data to the callback function or to a subroutine. In the
! 699: ** case of a subroutine, the subroutine itself is responsible for
! 700: ** popping the data from the stack.
! 701: */
! 702: case SRT_Coroutine:
! 703: case SRT_Output: {
! 704: testcase( eDest==SRT_Coroutine );
! 705: testcase( eDest==SRT_Output );
! 706: if( pOrderBy ){
! 707: int r1 = sqlite3GetTempReg(pParse);
! 708: sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
! 709: pushOntoSorter(pParse, pOrderBy, p, r1);
! 710: sqlite3ReleaseTempReg(pParse, r1);
! 711: }else if( eDest==SRT_Coroutine ){
! 712: sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm);
! 713: }else{
! 714: sqlite3VdbeAddOp2(v, OP_ResultRow, regResult, nColumn);
! 715: sqlite3ExprCacheAffinityChange(pParse, regResult, nColumn);
! 716: }
! 717: break;
! 718: }
! 719:
! 720: #if !defined(SQLITE_OMIT_TRIGGER)
! 721: /* Discard the results. This is used for SELECT statements inside
! 722: ** the body of a TRIGGER. The purpose of such selects is to call
! 723: ** user-defined functions that have side effects. We do not care
! 724: ** about the actual results of the select.
! 725: */
! 726: default: {
! 727: assert( eDest==SRT_Discard );
! 728: break;
! 729: }
! 730: #endif
! 731: }
! 732:
! 733: /* Jump to the end of the loop if the LIMIT is reached. Except, if
! 734: ** there is a sorter, in which case the sorter has already limited
! 735: ** the output for us.
! 736: */
! 737: if( pOrderBy==0 && p->iLimit ){
! 738: sqlite3VdbeAddOp3(v, OP_IfZero, p->iLimit, iBreak, -1);
! 739: }
! 740: }
! 741:
! 742: /*
! 743: ** Given an expression list, generate a KeyInfo structure that records
! 744: ** the collating sequence for each expression in that expression list.
! 745: **
! 746: ** If the ExprList is an ORDER BY or GROUP BY clause then the resulting
! 747: ** KeyInfo structure is appropriate for initializing a virtual index to
! 748: ** implement that clause. If the ExprList is the result set of a SELECT
! 749: ** then the KeyInfo structure is appropriate for initializing a virtual
! 750: ** index to implement a DISTINCT test.
! 751: **
! 752: ** Space to hold the KeyInfo structure is obtain from malloc. The calling
! 753: ** function is responsible for seeing that this structure is eventually
! 754: ** freed. Add the KeyInfo structure to the P4 field of an opcode using
! 755: ** P4_KEYINFO_HANDOFF is the usual way of dealing with this.
! 756: */
! 757: static KeyInfo *keyInfoFromExprList(Parse *pParse, ExprList *pList){
! 758: sqlite3 *db = pParse->db;
! 759: int nExpr;
! 760: KeyInfo *pInfo;
! 761: struct ExprList_item *pItem;
! 762: int i;
! 763:
! 764: nExpr = pList->nExpr;
! 765: pInfo = sqlite3DbMallocZero(db, sizeof(*pInfo) + nExpr*(sizeof(CollSeq*)+1) );
! 766: if( pInfo ){
! 767: pInfo->aSortOrder = (u8*)&pInfo->aColl[nExpr];
! 768: pInfo->nField = (u16)nExpr;
! 769: pInfo->enc = ENC(db);
! 770: pInfo->db = db;
! 771: for(i=0, pItem=pList->a; i<nExpr; i++, pItem++){
! 772: CollSeq *pColl;
! 773: pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
! 774: if( !pColl ){
! 775: pColl = db->pDfltColl;
! 776: }
! 777: pInfo->aColl[i] = pColl;
! 778: pInfo->aSortOrder[i] = pItem->sortOrder;
! 779: }
! 780: }
! 781: return pInfo;
! 782: }
! 783:
! 784: #ifndef SQLITE_OMIT_COMPOUND_SELECT
! 785: /*
! 786: ** Name of the connection operator, used for error messages.
! 787: */
! 788: static const char *selectOpName(int id){
! 789: char *z;
! 790: switch( id ){
! 791: case TK_ALL: z = "UNION ALL"; break;
! 792: case TK_INTERSECT: z = "INTERSECT"; break;
! 793: case TK_EXCEPT: z = "EXCEPT"; break;
! 794: default: z = "UNION"; break;
! 795: }
! 796: return z;
! 797: }
! 798: #endif /* SQLITE_OMIT_COMPOUND_SELECT */
! 799:
! 800: #ifndef SQLITE_OMIT_EXPLAIN
! 801: /*
! 802: ** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function
! 803: ** is a no-op. Otherwise, it adds a single row of output to the EQP result,
! 804: ** where the caption is of the form:
! 805: **
! 806: ** "USE TEMP B-TREE FOR xxx"
! 807: **
! 808: ** where xxx is one of "DISTINCT", "ORDER BY" or "GROUP BY". Exactly which
! 809: ** is determined by the zUsage argument.
! 810: */
! 811: static void explainTempTable(Parse *pParse, const char *zUsage){
! 812: if( pParse->explain==2 ){
! 813: Vdbe *v = pParse->pVdbe;
! 814: char *zMsg = sqlite3MPrintf(pParse->db, "USE TEMP B-TREE FOR %s", zUsage);
! 815: sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC);
! 816: }
! 817: }
! 818:
! 819: /*
! 820: ** Assign expression b to lvalue a. A second, no-op, version of this macro
! 821: ** is provided when SQLITE_OMIT_EXPLAIN is defined. This allows the code
! 822: ** in sqlite3Select() to assign values to structure member variables that
! 823: ** only exist if SQLITE_OMIT_EXPLAIN is not defined without polluting the
! 824: ** code with #ifndef directives.
! 825: */
! 826: # define explainSetInteger(a, b) a = b
! 827:
! 828: #else
! 829: /* No-op versions of the explainXXX() functions and macros. */
! 830: # define explainTempTable(y,z)
! 831: # define explainSetInteger(y,z)
! 832: #endif
! 833:
! 834: #if !defined(SQLITE_OMIT_EXPLAIN) && !defined(SQLITE_OMIT_COMPOUND_SELECT)
! 835: /*
! 836: ** Unless an "EXPLAIN QUERY PLAN" command is being processed, this function
! 837: ** is a no-op. Otherwise, it adds a single row of output to the EQP result,
! 838: ** where the caption is of one of the two forms:
! 839: **
! 840: ** "COMPOSITE SUBQUERIES iSub1 and iSub2 (op)"
! 841: ** "COMPOSITE SUBQUERIES iSub1 and iSub2 USING TEMP B-TREE (op)"
! 842: **
! 843: ** where iSub1 and iSub2 are the integers passed as the corresponding
! 844: ** function parameters, and op is the text representation of the parameter
! 845: ** of the same name. The parameter "op" must be one of TK_UNION, TK_EXCEPT,
! 846: ** TK_INTERSECT or TK_ALL. The first form is used if argument bUseTmp is
! 847: ** false, or the second form if it is true.
! 848: */
! 849: static void explainComposite(
! 850: Parse *pParse, /* Parse context */
! 851: int op, /* One of TK_UNION, TK_EXCEPT etc. */
! 852: int iSub1, /* Subquery id 1 */
! 853: int iSub2, /* Subquery id 2 */
! 854: int bUseTmp /* True if a temp table was used */
! 855: ){
! 856: assert( op==TK_UNION || op==TK_EXCEPT || op==TK_INTERSECT || op==TK_ALL );
! 857: if( pParse->explain==2 ){
! 858: Vdbe *v = pParse->pVdbe;
! 859: char *zMsg = sqlite3MPrintf(
! 860: pParse->db, "COMPOUND SUBQUERIES %d AND %d %s(%s)", iSub1, iSub2,
! 861: bUseTmp?"USING TEMP B-TREE ":"", selectOpName(op)
! 862: );
! 863: sqlite3VdbeAddOp4(v, OP_Explain, pParse->iSelectId, 0, 0, zMsg, P4_DYNAMIC);
! 864: }
! 865: }
! 866: #else
! 867: /* No-op versions of the explainXXX() functions and macros. */
! 868: # define explainComposite(v,w,x,y,z)
! 869: #endif
! 870:
! 871: /*
! 872: ** If the inner loop was generated using a non-null pOrderBy argument,
! 873: ** then the results were placed in a sorter. After the loop is terminated
! 874: ** we need to run the sorter and output the results. The following
! 875: ** routine generates the code needed to do that.
! 876: */
! 877: static void generateSortTail(
! 878: Parse *pParse, /* Parsing context */
! 879: Select *p, /* The SELECT statement */
! 880: Vdbe *v, /* Generate code into this VDBE */
! 881: int nColumn, /* Number of columns of data */
! 882: SelectDest *pDest /* Write the sorted results here */
! 883: ){
! 884: int addrBreak = sqlite3VdbeMakeLabel(v); /* Jump here to exit loop */
! 885: int addrContinue = sqlite3VdbeMakeLabel(v); /* Jump here for next cycle */
! 886: int addr;
! 887: int iTab;
! 888: int pseudoTab = 0;
! 889: ExprList *pOrderBy = p->pOrderBy;
! 890:
! 891: int eDest = pDest->eDest;
! 892: int iParm = pDest->iParm;
! 893:
! 894: int regRow;
! 895: int regRowid;
! 896:
! 897: iTab = pOrderBy->iECursor;
! 898: regRow = sqlite3GetTempReg(pParse);
! 899: if( eDest==SRT_Output || eDest==SRT_Coroutine ){
! 900: pseudoTab = pParse->nTab++;
! 901: sqlite3VdbeAddOp3(v, OP_OpenPseudo, pseudoTab, regRow, nColumn);
! 902: regRowid = 0;
! 903: }else{
! 904: regRowid = sqlite3GetTempReg(pParse);
! 905: }
! 906: if( p->selFlags & SF_UseSorter ){
! 907: int regSortOut = ++pParse->nMem;
! 908: int ptab2 = pParse->nTab++;
! 909: sqlite3VdbeAddOp3(v, OP_OpenPseudo, ptab2, regSortOut, pOrderBy->nExpr+2);
! 910: addr = 1 + sqlite3VdbeAddOp2(v, OP_SorterSort, iTab, addrBreak);
! 911: codeOffset(v, p, addrContinue);
! 912: sqlite3VdbeAddOp2(v, OP_SorterData, iTab, regSortOut);
! 913: sqlite3VdbeAddOp3(v, OP_Column, ptab2, pOrderBy->nExpr+1, regRow);
! 914: sqlite3VdbeChangeP5(v, OPFLAG_CLEARCACHE);
! 915: }else{
! 916: addr = 1 + sqlite3VdbeAddOp2(v, OP_Sort, iTab, addrBreak);
! 917: codeOffset(v, p, addrContinue);
! 918: sqlite3VdbeAddOp3(v, OP_Column, iTab, pOrderBy->nExpr+1, regRow);
! 919: }
! 920: switch( eDest ){
! 921: case SRT_Table:
! 922: case SRT_EphemTab: {
! 923: testcase( eDest==SRT_Table );
! 924: testcase( eDest==SRT_EphemTab );
! 925: sqlite3VdbeAddOp2(v, OP_NewRowid, iParm, regRowid);
! 926: sqlite3VdbeAddOp3(v, OP_Insert, iParm, regRow, regRowid);
! 927: sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
! 928: break;
! 929: }
! 930: #ifndef SQLITE_OMIT_SUBQUERY
! 931: case SRT_Set: {
! 932: assert( nColumn==1 );
! 933: sqlite3VdbeAddOp4(v, OP_MakeRecord, regRow, 1, regRowid, &p->affinity, 1);
! 934: sqlite3ExprCacheAffinityChange(pParse, regRow, 1);
! 935: sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm, regRowid);
! 936: break;
! 937: }
! 938: case SRT_Mem: {
! 939: assert( nColumn==1 );
! 940: sqlite3ExprCodeMove(pParse, regRow, iParm, 1);
! 941: /* The LIMIT clause will terminate the loop for us */
! 942: break;
! 943: }
! 944: #endif
! 945: default: {
! 946: int i;
! 947: assert( eDest==SRT_Output || eDest==SRT_Coroutine );
! 948: testcase( eDest==SRT_Output );
! 949: testcase( eDest==SRT_Coroutine );
! 950: for(i=0; i<nColumn; i++){
! 951: assert( regRow!=pDest->iMem+i );
! 952: sqlite3VdbeAddOp3(v, OP_Column, pseudoTab, i, pDest->iMem+i);
! 953: if( i==0 ){
! 954: sqlite3VdbeChangeP5(v, OPFLAG_CLEARCACHE);
! 955: }
! 956: }
! 957: if( eDest==SRT_Output ){
! 958: sqlite3VdbeAddOp2(v, OP_ResultRow, pDest->iMem, nColumn);
! 959: sqlite3ExprCacheAffinityChange(pParse, pDest->iMem, nColumn);
! 960: }else{
! 961: sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm);
! 962: }
! 963: break;
! 964: }
! 965: }
! 966: sqlite3ReleaseTempReg(pParse, regRow);
! 967: sqlite3ReleaseTempReg(pParse, regRowid);
! 968:
! 969: /* The bottom of the loop
! 970: */
! 971: sqlite3VdbeResolveLabel(v, addrContinue);
! 972: if( p->selFlags & SF_UseSorter ){
! 973: sqlite3VdbeAddOp2(v, OP_SorterNext, iTab, addr);
! 974: }else{
! 975: sqlite3VdbeAddOp2(v, OP_Next, iTab, addr);
! 976: }
! 977: sqlite3VdbeResolveLabel(v, addrBreak);
! 978: if( eDest==SRT_Output || eDest==SRT_Coroutine ){
! 979: sqlite3VdbeAddOp2(v, OP_Close, pseudoTab, 0);
! 980: }
! 981: }
! 982:
! 983: /*
! 984: ** Return a pointer to a string containing the 'declaration type' of the
! 985: ** expression pExpr. The string may be treated as static by the caller.
! 986: **
! 987: ** The declaration type is the exact datatype definition extracted from the
! 988: ** original CREATE TABLE statement if the expression is a column. The
! 989: ** declaration type for a ROWID field is INTEGER. Exactly when an expression
! 990: ** is considered a column can be complex in the presence of subqueries. The
! 991: ** result-set expression in all of the following SELECT statements is
! 992: ** considered a column by this function.
! 993: **
! 994: ** SELECT col FROM tbl;
! 995: ** SELECT (SELECT col FROM tbl;
! 996: ** SELECT (SELECT col FROM tbl);
! 997: ** SELECT abc FROM (SELECT col AS abc FROM tbl);
! 998: **
! 999: ** The declaration type for any expression other than a column is NULL.
! 1000: */
! 1001: static const char *columnType(
! 1002: NameContext *pNC,
! 1003: Expr *pExpr,
! 1004: const char **pzOriginDb,
! 1005: const char **pzOriginTab,
! 1006: const char **pzOriginCol
! 1007: ){
! 1008: char const *zType = 0;
! 1009: char const *zOriginDb = 0;
! 1010: char const *zOriginTab = 0;
! 1011: char const *zOriginCol = 0;
! 1012: int j;
! 1013: if( NEVER(pExpr==0) || pNC->pSrcList==0 ) return 0;
! 1014:
! 1015: switch( pExpr->op ){
! 1016: case TK_AGG_COLUMN:
! 1017: case TK_COLUMN: {
! 1018: /* The expression is a column. Locate the table the column is being
! 1019: ** extracted from in NameContext.pSrcList. This table may be real
! 1020: ** database table or a subquery.
! 1021: */
! 1022: Table *pTab = 0; /* Table structure column is extracted from */
! 1023: Select *pS = 0; /* Select the column is extracted from */
! 1024: int iCol = pExpr->iColumn; /* Index of column in pTab */
! 1025: testcase( pExpr->op==TK_AGG_COLUMN );
! 1026: testcase( pExpr->op==TK_COLUMN );
! 1027: while( pNC && !pTab ){
! 1028: SrcList *pTabList = pNC->pSrcList;
! 1029: for(j=0;j<pTabList->nSrc && pTabList->a[j].iCursor!=pExpr->iTable;j++);
! 1030: if( j<pTabList->nSrc ){
! 1031: pTab = pTabList->a[j].pTab;
! 1032: pS = pTabList->a[j].pSelect;
! 1033: }else{
! 1034: pNC = pNC->pNext;
! 1035: }
! 1036: }
! 1037:
! 1038: if( pTab==0 ){
! 1039: /* At one time, code such as "SELECT new.x" within a trigger would
! 1040: ** cause this condition to run. Since then, we have restructured how
! 1041: ** trigger code is generated and so this condition is no longer
! 1042: ** possible. However, it can still be true for statements like
! 1043: ** the following:
! 1044: **
! 1045: ** CREATE TABLE t1(col INTEGER);
! 1046: ** SELECT (SELECT t1.col) FROM FROM t1;
! 1047: **
! 1048: ** when columnType() is called on the expression "t1.col" in the
! 1049: ** sub-select. In this case, set the column type to NULL, even
! 1050: ** though it should really be "INTEGER".
! 1051: **
! 1052: ** This is not a problem, as the column type of "t1.col" is never
! 1053: ** used. When columnType() is called on the expression
! 1054: ** "(SELECT t1.col)", the correct type is returned (see the TK_SELECT
! 1055: ** branch below. */
! 1056: break;
! 1057: }
! 1058:
! 1059: assert( pTab && pExpr->pTab==pTab );
! 1060: if( pS ){
! 1061: /* The "table" is actually a sub-select or a view in the FROM clause
! 1062: ** of the SELECT statement. Return the declaration type and origin
! 1063: ** data for the result-set column of the sub-select.
! 1064: */
! 1065: if( iCol>=0 && ALWAYS(iCol<pS->pEList->nExpr) ){
! 1066: /* If iCol is less than zero, then the expression requests the
! 1067: ** rowid of the sub-select or view. This expression is legal (see
! 1068: ** test case misc2.2.2) - it always evaluates to NULL.
! 1069: */
! 1070: NameContext sNC;
! 1071: Expr *p = pS->pEList->a[iCol].pExpr;
! 1072: sNC.pSrcList = pS->pSrc;
! 1073: sNC.pNext = pNC;
! 1074: sNC.pParse = pNC->pParse;
! 1075: zType = columnType(&sNC, p, &zOriginDb, &zOriginTab, &zOriginCol);
! 1076: }
! 1077: }else if( ALWAYS(pTab->pSchema) ){
! 1078: /* A real table */
! 1079: assert( !pS );
! 1080: if( iCol<0 ) iCol = pTab->iPKey;
! 1081: assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
! 1082: if( iCol<0 ){
! 1083: zType = "INTEGER";
! 1084: zOriginCol = "rowid";
! 1085: }else{
! 1086: zType = pTab->aCol[iCol].zType;
! 1087: zOriginCol = pTab->aCol[iCol].zName;
! 1088: }
! 1089: zOriginTab = pTab->zName;
! 1090: if( pNC->pParse ){
! 1091: int iDb = sqlite3SchemaToIndex(pNC->pParse->db, pTab->pSchema);
! 1092: zOriginDb = pNC->pParse->db->aDb[iDb].zName;
! 1093: }
! 1094: }
! 1095: break;
! 1096: }
! 1097: #ifndef SQLITE_OMIT_SUBQUERY
! 1098: case TK_SELECT: {
! 1099: /* The expression is a sub-select. Return the declaration type and
! 1100: ** origin info for the single column in the result set of the SELECT
! 1101: ** statement.
! 1102: */
! 1103: NameContext sNC;
! 1104: Select *pS = pExpr->x.pSelect;
! 1105: Expr *p = pS->pEList->a[0].pExpr;
! 1106: assert( ExprHasProperty(pExpr, EP_xIsSelect) );
! 1107: sNC.pSrcList = pS->pSrc;
! 1108: sNC.pNext = pNC;
! 1109: sNC.pParse = pNC->pParse;
! 1110: zType = columnType(&sNC, p, &zOriginDb, &zOriginTab, &zOriginCol);
! 1111: break;
! 1112: }
! 1113: #endif
! 1114: }
! 1115:
! 1116: if( pzOriginDb ){
! 1117: assert( pzOriginTab && pzOriginCol );
! 1118: *pzOriginDb = zOriginDb;
! 1119: *pzOriginTab = zOriginTab;
! 1120: *pzOriginCol = zOriginCol;
! 1121: }
! 1122: return zType;
! 1123: }
! 1124:
! 1125: /*
! 1126: ** Generate code that will tell the VDBE the declaration types of columns
! 1127: ** in the result set.
! 1128: */
! 1129: static void generateColumnTypes(
! 1130: Parse *pParse, /* Parser context */
! 1131: SrcList *pTabList, /* List of tables */
! 1132: ExprList *pEList /* Expressions defining the result set */
! 1133: ){
! 1134: #ifndef SQLITE_OMIT_DECLTYPE
! 1135: Vdbe *v = pParse->pVdbe;
! 1136: int i;
! 1137: NameContext sNC;
! 1138: sNC.pSrcList = pTabList;
! 1139: sNC.pParse = pParse;
! 1140: for(i=0; i<pEList->nExpr; i++){
! 1141: Expr *p = pEList->a[i].pExpr;
! 1142: const char *zType;
! 1143: #ifdef SQLITE_ENABLE_COLUMN_METADATA
! 1144: const char *zOrigDb = 0;
! 1145: const char *zOrigTab = 0;
! 1146: const char *zOrigCol = 0;
! 1147: zType = columnType(&sNC, p, &zOrigDb, &zOrigTab, &zOrigCol);
! 1148:
! 1149: /* The vdbe must make its own copy of the column-type and other
! 1150: ** column specific strings, in case the schema is reset before this
! 1151: ** virtual machine is deleted.
! 1152: */
! 1153: sqlite3VdbeSetColName(v, i, COLNAME_DATABASE, zOrigDb, SQLITE_TRANSIENT);
! 1154: sqlite3VdbeSetColName(v, i, COLNAME_TABLE, zOrigTab, SQLITE_TRANSIENT);
! 1155: sqlite3VdbeSetColName(v, i, COLNAME_COLUMN, zOrigCol, SQLITE_TRANSIENT);
! 1156: #else
! 1157: zType = columnType(&sNC, p, 0, 0, 0);
! 1158: #endif
! 1159: sqlite3VdbeSetColName(v, i, COLNAME_DECLTYPE, zType, SQLITE_TRANSIENT);
! 1160: }
! 1161: #endif /* SQLITE_OMIT_DECLTYPE */
! 1162: }
! 1163:
! 1164: /*
! 1165: ** Generate code that will tell the VDBE the names of columns
! 1166: ** in the result set. This information is used to provide the
! 1167: ** azCol[] values in the callback.
! 1168: */
! 1169: static void generateColumnNames(
! 1170: Parse *pParse, /* Parser context */
! 1171: SrcList *pTabList, /* List of tables */
! 1172: ExprList *pEList /* Expressions defining the result set */
! 1173: ){
! 1174: Vdbe *v = pParse->pVdbe;
! 1175: int i, j;
! 1176: sqlite3 *db = pParse->db;
! 1177: int fullNames, shortNames;
! 1178:
! 1179: #ifndef SQLITE_OMIT_EXPLAIN
! 1180: /* If this is an EXPLAIN, skip this step */
! 1181: if( pParse->explain ){
! 1182: return;
! 1183: }
! 1184: #endif
! 1185:
! 1186: if( pParse->colNamesSet || NEVER(v==0) || db->mallocFailed ) return;
! 1187: pParse->colNamesSet = 1;
! 1188: fullNames = (db->flags & SQLITE_FullColNames)!=0;
! 1189: shortNames = (db->flags & SQLITE_ShortColNames)!=0;
! 1190: sqlite3VdbeSetNumCols(v, pEList->nExpr);
! 1191: for(i=0; i<pEList->nExpr; i++){
! 1192: Expr *p;
! 1193: p = pEList->a[i].pExpr;
! 1194: if( NEVER(p==0) ) continue;
! 1195: if( pEList->a[i].zName ){
! 1196: char *zName = pEList->a[i].zName;
! 1197: sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_TRANSIENT);
! 1198: }else if( (p->op==TK_COLUMN || p->op==TK_AGG_COLUMN) && pTabList ){
! 1199: Table *pTab;
! 1200: char *zCol;
! 1201: int iCol = p->iColumn;
! 1202: for(j=0; ALWAYS(j<pTabList->nSrc); j++){
! 1203: if( pTabList->a[j].iCursor==p->iTable ) break;
! 1204: }
! 1205: assert( j<pTabList->nSrc );
! 1206: pTab = pTabList->a[j].pTab;
! 1207: if( iCol<0 ) iCol = pTab->iPKey;
! 1208: assert( iCol==-1 || (iCol>=0 && iCol<pTab->nCol) );
! 1209: if( iCol<0 ){
! 1210: zCol = "rowid";
! 1211: }else{
! 1212: zCol = pTab->aCol[iCol].zName;
! 1213: }
! 1214: if( !shortNames && !fullNames ){
! 1215: sqlite3VdbeSetColName(v, i, COLNAME_NAME,
! 1216: sqlite3DbStrDup(db, pEList->a[i].zSpan), SQLITE_DYNAMIC);
! 1217: }else if( fullNames ){
! 1218: char *zName = 0;
! 1219: zName = sqlite3MPrintf(db, "%s.%s", pTab->zName, zCol);
! 1220: sqlite3VdbeSetColName(v, i, COLNAME_NAME, zName, SQLITE_DYNAMIC);
! 1221: }else{
! 1222: sqlite3VdbeSetColName(v, i, COLNAME_NAME, zCol, SQLITE_TRANSIENT);
! 1223: }
! 1224: }else{
! 1225: sqlite3VdbeSetColName(v, i, COLNAME_NAME,
! 1226: sqlite3DbStrDup(db, pEList->a[i].zSpan), SQLITE_DYNAMIC);
! 1227: }
! 1228: }
! 1229: generateColumnTypes(pParse, pTabList, pEList);
! 1230: }
! 1231:
! 1232: /*
! 1233: ** Given a an expression list (which is really the list of expressions
! 1234: ** that form the result set of a SELECT statement) compute appropriate
! 1235: ** column names for a table that would hold the expression list.
! 1236: **
! 1237: ** All column names will be unique.
! 1238: **
! 1239: ** Only the column names are computed. Column.zType, Column.zColl,
! 1240: ** and other fields of Column are zeroed.
! 1241: **
! 1242: ** Return SQLITE_OK on success. If a memory allocation error occurs,
! 1243: ** store NULL in *paCol and 0 in *pnCol and return SQLITE_NOMEM.
! 1244: */
! 1245: static int selectColumnsFromExprList(
! 1246: Parse *pParse, /* Parsing context */
! 1247: ExprList *pEList, /* Expr list from which to derive column names */
! 1248: int *pnCol, /* Write the number of columns here */
! 1249: Column **paCol /* Write the new column list here */
! 1250: ){
! 1251: sqlite3 *db = pParse->db; /* Database connection */
! 1252: int i, j; /* Loop counters */
! 1253: int cnt; /* Index added to make the name unique */
! 1254: Column *aCol, *pCol; /* For looping over result columns */
! 1255: int nCol; /* Number of columns in the result set */
! 1256: Expr *p; /* Expression for a single result column */
! 1257: char *zName; /* Column name */
! 1258: int nName; /* Size of name in zName[] */
! 1259:
! 1260: *pnCol = nCol = pEList->nExpr;
! 1261: aCol = *paCol = sqlite3DbMallocZero(db, sizeof(aCol[0])*nCol);
! 1262: if( aCol==0 ) return SQLITE_NOMEM;
! 1263: for(i=0, pCol=aCol; i<nCol; i++, pCol++){
! 1264: /* Get an appropriate name for the column
! 1265: */
! 1266: p = pEList->a[i].pExpr;
! 1267: assert( p->pRight==0 || ExprHasProperty(p->pRight, EP_IntValue)
! 1268: || p->pRight->u.zToken==0 || p->pRight->u.zToken[0]!=0 );
! 1269: if( (zName = pEList->a[i].zName)!=0 ){
! 1270: /* If the column contains an "AS <name>" phrase, use <name> as the name */
! 1271: zName = sqlite3DbStrDup(db, zName);
! 1272: }else{
! 1273: Expr *pColExpr = p; /* The expression that is the result column name */
! 1274: Table *pTab; /* Table associated with this expression */
! 1275: while( pColExpr->op==TK_DOT ){
! 1276: pColExpr = pColExpr->pRight;
! 1277: assert( pColExpr!=0 );
! 1278: }
! 1279: if( pColExpr->op==TK_COLUMN && ALWAYS(pColExpr->pTab!=0) ){
! 1280: /* For columns use the column name name */
! 1281: int iCol = pColExpr->iColumn;
! 1282: pTab = pColExpr->pTab;
! 1283: if( iCol<0 ) iCol = pTab->iPKey;
! 1284: zName = sqlite3MPrintf(db, "%s",
! 1285: iCol>=0 ? pTab->aCol[iCol].zName : "rowid");
! 1286: }else if( pColExpr->op==TK_ID ){
! 1287: assert( !ExprHasProperty(pColExpr, EP_IntValue) );
! 1288: zName = sqlite3MPrintf(db, "%s", pColExpr->u.zToken);
! 1289: }else{
! 1290: /* Use the original text of the column expression as its name */
! 1291: zName = sqlite3MPrintf(db, "%s", pEList->a[i].zSpan);
! 1292: }
! 1293: }
! 1294: if( db->mallocFailed ){
! 1295: sqlite3DbFree(db, zName);
! 1296: break;
! 1297: }
! 1298:
! 1299: /* Make sure the column name is unique. If the name is not unique,
! 1300: ** append a integer to the name so that it becomes unique.
! 1301: */
! 1302: nName = sqlite3Strlen30(zName);
! 1303: for(j=cnt=0; j<i; j++){
! 1304: if( sqlite3StrICmp(aCol[j].zName, zName)==0 ){
! 1305: char *zNewName;
! 1306: zName[nName] = 0;
! 1307: zNewName = sqlite3MPrintf(db, "%s:%d", zName, ++cnt);
! 1308: sqlite3DbFree(db, zName);
! 1309: zName = zNewName;
! 1310: j = -1;
! 1311: if( zName==0 ) break;
! 1312: }
! 1313: }
! 1314: pCol->zName = zName;
! 1315: }
! 1316: if( db->mallocFailed ){
! 1317: for(j=0; j<i; j++){
! 1318: sqlite3DbFree(db, aCol[j].zName);
! 1319: }
! 1320: sqlite3DbFree(db, aCol);
! 1321: *paCol = 0;
! 1322: *pnCol = 0;
! 1323: return SQLITE_NOMEM;
! 1324: }
! 1325: return SQLITE_OK;
! 1326: }
! 1327:
! 1328: /*
! 1329: ** Add type and collation information to a column list based on
! 1330: ** a SELECT statement.
! 1331: **
! 1332: ** The column list presumably came from selectColumnNamesFromExprList().
! 1333: ** The column list has only names, not types or collations. This
! 1334: ** routine goes through and adds the types and collations.
! 1335: **
! 1336: ** This routine requires that all identifiers in the SELECT
! 1337: ** statement be resolved.
! 1338: */
! 1339: static void selectAddColumnTypeAndCollation(
! 1340: Parse *pParse, /* Parsing contexts */
! 1341: int nCol, /* Number of columns */
! 1342: Column *aCol, /* List of columns */
! 1343: Select *pSelect /* SELECT used to determine types and collations */
! 1344: ){
! 1345: sqlite3 *db = pParse->db;
! 1346: NameContext sNC;
! 1347: Column *pCol;
! 1348: CollSeq *pColl;
! 1349: int i;
! 1350: Expr *p;
! 1351: struct ExprList_item *a;
! 1352:
! 1353: assert( pSelect!=0 );
! 1354: assert( (pSelect->selFlags & SF_Resolved)!=0 );
! 1355: assert( nCol==pSelect->pEList->nExpr || db->mallocFailed );
! 1356: if( db->mallocFailed ) return;
! 1357: memset(&sNC, 0, sizeof(sNC));
! 1358: sNC.pSrcList = pSelect->pSrc;
! 1359: a = pSelect->pEList->a;
! 1360: for(i=0, pCol=aCol; i<nCol; i++, pCol++){
! 1361: p = a[i].pExpr;
! 1362: pCol->zType = sqlite3DbStrDup(db, columnType(&sNC, p, 0, 0, 0));
! 1363: pCol->affinity = sqlite3ExprAffinity(p);
! 1364: if( pCol->affinity==0 ) pCol->affinity = SQLITE_AFF_NONE;
! 1365: pColl = sqlite3ExprCollSeq(pParse, p);
! 1366: if( pColl ){
! 1367: pCol->zColl = sqlite3DbStrDup(db, pColl->zName);
! 1368: }
! 1369: }
! 1370: }
! 1371:
! 1372: /*
! 1373: ** Given a SELECT statement, generate a Table structure that describes
! 1374: ** the result set of that SELECT.
! 1375: */
! 1376: Table *sqlite3ResultSetOfSelect(Parse *pParse, Select *pSelect){
! 1377: Table *pTab;
! 1378: sqlite3 *db = pParse->db;
! 1379: int savedFlags;
! 1380:
! 1381: savedFlags = db->flags;
! 1382: db->flags &= ~SQLITE_FullColNames;
! 1383: db->flags |= SQLITE_ShortColNames;
! 1384: sqlite3SelectPrep(pParse, pSelect, 0);
! 1385: if( pParse->nErr ) return 0;
! 1386: while( pSelect->pPrior ) pSelect = pSelect->pPrior;
! 1387: db->flags = savedFlags;
! 1388: pTab = sqlite3DbMallocZero(db, sizeof(Table) );
! 1389: if( pTab==0 ){
! 1390: return 0;
! 1391: }
! 1392: /* The sqlite3ResultSetOfSelect() is only used n contexts where lookaside
! 1393: ** is disabled */
! 1394: assert( db->lookaside.bEnabled==0 );
! 1395: pTab->nRef = 1;
! 1396: pTab->zName = 0;
! 1397: pTab->nRowEst = 1000000;
! 1398: selectColumnsFromExprList(pParse, pSelect->pEList, &pTab->nCol, &pTab->aCol);
! 1399: selectAddColumnTypeAndCollation(pParse, pTab->nCol, pTab->aCol, pSelect);
! 1400: pTab->iPKey = -1;
! 1401: if( db->mallocFailed ){
! 1402: sqlite3DeleteTable(db, pTab);
! 1403: return 0;
! 1404: }
! 1405: return pTab;
! 1406: }
! 1407:
! 1408: /*
! 1409: ** Get a VDBE for the given parser context. Create a new one if necessary.
! 1410: ** If an error occurs, return NULL and leave a message in pParse.
! 1411: */
! 1412: Vdbe *sqlite3GetVdbe(Parse *pParse){
! 1413: Vdbe *v = pParse->pVdbe;
! 1414: if( v==0 ){
! 1415: v = pParse->pVdbe = sqlite3VdbeCreate(pParse->db);
! 1416: #ifndef SQLITE_OMIT_TRACE
! 1417: if( v ){
! 1418: sqlite3VdbeAddOp0(v, OP_Trace);
! 1419: }
! 1420: #endif
! 1421: }
! 1422: return v;
! 1423: }
! 1424:
! 1425:
! 1426: /*
! 1427: ** Compute the iLimit and iOffset fields of the SELECT based on the
! 1428: ** pLimit and pOffset expressions. pLimit and pOffset hold the expressions
! 1429: ** that appear in the original SQL statement after the LIMIT and OFFSET
! 1430: ** keywords. Or NULL if those keywords are omitted. iLimit and iOffset
! 1431: ** are the integer memory register numbers for counters used to compute
! 1432: ** the limit and offset. If there is no limit and/or offset, then
! 1433: ** iLimit and iOffset are negative.
! 1434: **
! 1435: ** This routine changes the values of iLimit and iOffset only if
! 1436: ** a limit or offset is defined by pLimit and pOffset. iLimit and
! 1437: ** iOffset should have been preset to appropriate default values
! 1438: ** (usually but not always -1) prior to calling this routine.
! 1439: ** Only if pLimit!=0 or pOffset!=0 do the limit registers get
! 1440: ** redefined. The UNION ALL operator uses this property to force
! 1441: ** the reuse of the same limit and offset registers across multiple
! 1442: ** SELECT statements.
! 1443: */
! 1444: static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){
! 1445: Vdbe *v = 0;
! 1446: int iLimit = 0;
! 1447: int iOffset;
! 1448: int addr1, n;
! 1449: if( p->iLimit ) return;
! 1450:
! 1451: /*
! 1452: ** "LIMIT -1" always shows all rows. There is some
! 1453: ** contraversy about what the correct behavior should be.
! 1454: ** The current implementation interprets "LIMIT 0" to mean
! 1455: ** no rows.
! 1456: */
! 1457: sqlite3ExprCacheClear(pParse);
! 1458: assert( p->pOffset==0 || p->pLimit!=0 );
! 1459: if( p->pLimit ){
! 1460: p->iLimit = iLimit = ++pParse->nMem;
! 1461: v = sqlite3GetVdbe(pParse);
! 1462: if( NEVER(v==0) ) return; /* VDBE should have already been allocated */
! 1463: if( sqlite3ExprIsInteger(p->pLimit, &n) ){
! 1464: sqlite3VdbeAddOp2(v, OP_Integer, n, iLimit);
! 1465: VdbeComment((v, "LIMIT counter"));
! 1466: if( n==0 ){
! 1467: sqlite3VdbeAddOp2(v, OP_Goto, 0, iBreak);
! 1468: }else{
! 1469: if( p->nSelectRow > (double)n ) p->nSelectRow = (double)n;
! 1470: }
! 1471: }else{
! 1472: sqlite3ExprCode(pParse, p->pLimit, iLimit);
! 1473: sqlite3VdbeAddOp1(v, OP_MustBeInt, iLimit);
! 1474: VdbeComment((v, "LIMIT counter"));
! 1475: sqlite3VdbeAddOp2(v, OP_IfZero, iLimit, iBreak);
! 1476: }
! 1477: if( p->pOffset ){
! 1478: p->iOffset = iOffset = ++pParse->nMem;
! 1479: pParse->nMem++; /* Allocate an extra register for limit+offset */
! 1480: sqlite3ExprCode(pParse, p->pOffset, iOffset);
! 1481: sqlite3VdbeAddOp1(v, OP_MustBeInt, iOffset);
! 1482: VdbeComment((v, "OFFSET counter"));
! 1483: addr1 = sqlite3VdbeAddOp1(v, OP_IfPos, iOffset);
! 1484: sqlite3VdbeAddOp2(v, OP_Integer, 0, iOffset);
! 1485: sqlite3VdbeJumpHere(v, addr1);
! 1486: sqlite3VdbeAddOp3(v, OP_Add, iLimit, iOffset, iOffset+1);
! 1487: VdbeComment((v, "LIMIT+OFFSET"));
! 1488: addr1 = sqlite3VdbeAddOp1(v, OP_IfPos, iLimit);
! 1489: sqlite3VdbeAddOp2(v, OP_Integer, -1, iOffset+1);
! 1490: sqlite3VdbeJumpHere(v, addr1);
! 1491: }
! 1492: }
! 1493: }
! 1494:
! 1495: #ifndef SQLITE_OMIT_COMPOUND_SELECT
! 1496: /*
! 1497: ** Return the appropriate collating sequence for the iCol-th column of
! 1498: ** the result set for the compound-select statement "p". Return NULL if
! 1499: ** the column has no default collating sequence.
! 1500: **
! 1501: ** The collating sequence for the compound select is taken from the
! 1502: ** left-most term of the select that has a collating sequence.
! 1503: */
! 1504: static CollSeq *multiSelectCollSeq(Parse *pParse, Select *p, int iCol){
! 1505: CollSeq *pRet;
! 1506: if( p->pPrior ){
! 1507: pRet = multiSelectCollSeq(pParse, p->pPrior, iCol);
! 1508: }else{
! 1509: pRet = 0;
! 1510: }
! 1511: assert( iCol>=0 );
! 1512: if( pRet==0 && iCol<p->pEList->nExpr ){
! 1513: pRet = sqlite3ExprCollSeq(pParse, p->pEList->a[iCol].pExpr);
! 1514: }
! 1515: return pRet;
! 1516: }
! 1517: #endif /* SQLITE_OMIT_COMPOUND_SELECT */
! 1518:
! 1519: /* Forward reference */
! 1520: static int multiSelectOrderBy(
! 1521: Parse *pParse, /* Parsing context */
! 1522: Select *p, /* The right-most of SELECTs to be coded */
! 1523: SelectDest *pDest /* What to do with query results */
! 1524: );
! 1525:
! 1526:
! 1527: #ifndef SQLITE_OMIT_COMPOUND_SELECT
! 1528: /*
! 1529: ** This routine is called to process a compound query form from
! 1530: ** two or more separate queries using UNION, UNION ALL, EXCEPT, or
! 1531: ** INTERSECT
! 1532: **
! 1533: ** "p" points to the right-most of the two queries. the query on the
! 1534: ** left is p->pPrior. The left query could also be a compound query
! 1535: ** in which case this routine will be called recursively.
! 1536: **
! 1537: ** The results of the total query are to be written into a destination
! 1538: ** of type eDest with parameter iParm.
! 1539: **
! 1540: ** Example 1: Consider a three-way compound SQL statement.
! 1541: **
! 1542: ** SELECT a FROM t1 UNION SELECT b FROM t2 UNION SELECT c FROM t3
! 1543: **
! 1544: ** This statement is parsed up as follows:
! 1545: **
! 1546: ** SELECT c FROM t3
! 1547: ** |
! 1548: ** `-----> SELECT b FROM t2
! 1549: ** |
! 1550: ** `------> SELECT a FROM t1
! 1551: **
! 1552: ** The arrows in the diagram above represent the Select.pPrior pointer.
! 1553: ** So if this routine is called with p equal to the t3 query, then
! 1554: ** pPrior will be the t2 query. p->op will be TK_UNION in this case.
! 1555: **
! 1556: ** Notice that because of the way SQLite parses compound SELECTs, the
! 1557: ** individual selects always group from left to right.
! 1558: */
! 1559: static int multiSelect(
! 1560: Parse *pParse, /* Parsing context */
! 1561: Select *p, /* The right-most of SELECTs to be coded */
! 1562: SelectDest *pDest /* What to do with query results */
! 1563: ){
! 1564: int rc = SQLITE_OK; /* Success code from a subroutine */
! 1565: Select *pPrior; /* Another SELECT immediately to our left */
! 1566: Vdbe *v; /* Generate code to this VDBE */
! 1567: SelectDest dest; /* Alternative data destination */
! 1568: Select *pDelete = 0; /* Chain of simple selects to delete */
! 1569: sqlite3 *db; /* Database connection */
! 1570: #ifndef SQLITE_OMIT_EXPLAIN
! 1571: int iSub1; /* EQP id of left-hand query */
! 1572: int iSub2; /* EQP id of right-hand query */
! 1573: #endif
! 1574:
! 1575: /* Make sure there is no ORDER BY or LIMIT clause on prior SELECTs. Only
! 1576: ** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT.
! 1577: */
! 1578: assert( p && p->pPrior ); /* Calling function guarantees this much */
! 1579: db = pParse->db;
! 1580: pPrior = p->pPrior;
! 1581: assert( pPrior->pRightmost!=pPrior );
! 1582: assert( pPrior->pRightmost==p->pRightmost );
! 1583: dest = *pDest;
! 1584: if( pPrior->pOrderBy ){
! 1585: sqlite3ErrorMsg(pParse,"ORDER BY clause should come after %s not before",
! 1586: selectOpName(p->op));
! 1587: rc = 1;
! 1588: goto multi_select_end;
! 1589: }
! 1590: if( pPrior->pLimit ){
! 1591: sqlite3ErrorMsg(pParse,"LIMIT clause should come after %s not before",
! 1592: selectOpName(p->op));
! 1593: rc = 1;
! 1594: goto multi_select_end;
! 1595: }
! 1596:
! 1597: v = sqlite3GetVdbe(pParse);
! 1598: assert( v!=0 ); /* The VDBE already created by calling function */
! 1599:
! 1600: /* Create the destination temporary table if necessary
! 1601: */
! 1602: if( dest.eDest==SRT_EphemTab ){
! 1603: assert( p->pEList );
! 1604: sqlite3VdbeAddOp2(v, OP_OpenEphemeral, dest.iParm, p->pEList->nExpr);
! 1605: sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
! 1606: dest.eDest = SRT_Table;
! 1607: }
! 1608:
! 1609: /* Make sure all SELECTs in the statement have the same number of elements
! 1610: ** in their result sets.
! 1611: */
! 1612: assert( p->pEList && pPrior->pEList );
! 1613: if( p->pEList->nExpr!=pPrior->pEList->nExpr ){
! 1614: sqlite3ErrorMsg(pParse, "SELECTs to the left and right of %s"
! 1615: " do not have the same number of result columns", selectOpName(p->op));
! 1616: rc = 1;
! 1617: goto multi_select_end;
! 1618: }
! 1619:
! 1620: /* Compound SELECTs that have an ORDER BY clause are handled separately.
! 1621: */
! 1622: if( p->pOrderBy ){
! 1623: return multiSelectOrderBy(pParse, p, pDest);
! 1624: }
! 1625:
! 1626: /* Generate code for the left and right SELECT statements.
! 1627: */
! 1628: switch( p->op ){
! 1629: case TK_ALL: {
! 1630: int addr = 0;
! 1631: int nLimit;
! 1632: assert( !pPrior->pLimit );
! 1633: pPrior->pLimit = p->pLimit;
! 1634: pPrior->pOffset = p->pOffset;
! 1635: explainSetInteger(iSub1, pParse->iNextSelectId);
! 1636: rc = sqlite3Select(pParse, pPrior, &dest);
! 1637: p->pLimit = 0;
! 1638: p->pOffset = 0;
! 1639: if( rc ){
! 1640: goto multi_select_end;
! 1641: }
! 1642: p->pPrior = 0;
! 1643: p->iLimit = pPrior->iLimit;
! 1644: p->iOffset = pPrior->iOffset;
! 1645: if( p->iLimit ){
! 1646: addr = sqlite3VdbeAddOp1(v, OP_IfZero, p->iLimit);
! 1647: VdbeComment((v, "Jump ahead if LIMIT reached"));
! 1648: }
! 1649: explainSetInteger(iSub2, pParse->iNextSelectId);
! 1650: rc = sqlite3Select(pParse, p, &dest);
! 1651: testcase( rc!=SQLITE_OK );
! 1652: pDelete = p->pPrior;
! 1653: p->pPrior = pPrior;
! 1654: p->nSelectRow += pPrior->nSelectRow;
! 1655: if( pPrior->pLimit
! 1656: && sqlite3ExprIsInteger(pPrior->pLimit, &nLimit)
! 1657: && p->nSelectRow > (double)nLimit
! 1658: ){
! 1659: p->nSelectRow = (double)nLimit;
! 1660: }
! 1661: if( addr ){
! 1662: sqlite3VdbeJumpHere(v, addr);
! 1663: }
! 1664: break;
! 1665: }
! 1666: case TK_EXCEPT:
! 1667: case TK_UNION: {
! 1668: int unionTab; /* Cursor number of the temporary table holding result */
! 1669: u8 op = 0; /* One of the SRT_ operations to apply to self */
! 1670: int priorOp; /* The SRT_ operation to apply to prior selects */
! 1671: Expr *pLimit, *pOffset; /* Saved values of p->nLimit and p->nOffset */
! 1672: int addr;
! 1673: SelectDest uniondest;
! 1674:
! 1675: testcase( p->op==TK_EXCEPT );
! 1676: testcase( p->op==TK_UNION );
! 1677: priorOp = SRT_Union;
! 1678: if( dest.eDest==priorOp && ALWAYS(!p->pLimit &&!p->pOffset) ){
! 1679: /* We can reuse a temporary table generated by a SELECT to our
! 1680: ** right.
! 1681: */
! 1682: assert( p->pRightmost!=p ); /* Can only happen for leftward elements
! 1683: ** of a 3-way or more compound */
! 1684: assert( p->pLimit==0 ); /* Not allowed on leftward elements */
! 1685: assert( p->pOffset==0 ); /* Not allowed on leftward elements */
! 1686: unionTab = dest.iParm;
! 1687: }else{
! 1688: /* We will need to create our own temporary table to hold the
! 1689: ** intermediate results.
! 1690: */
! 1691: unionTab = pParse->nTab++;
! 1692: assert( p->pOrderBy==0 );
! 1693: addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, unionTab, 0);
! 1694: assert( p->addrOpenEphm[0] == -1 );
! 1695: p->addrOpenEphm[0] = addr;
! 1696: p->pRightmost->selFlags |= SF_UsesEphemeral;
! 1697: assert( p->pEList );
! 1698: }
! 1699:
! 1700: /* Code the SELECT statements to our left
! 1701: */
! 1702: assert( !pPrior->pOrderBy );
! 1703: sqlite3SelectDestInit(&uniondest, priorOp, unionTab);
! 1704: explainSetInteger(iSub1, pParse->iNextSelectId);
! 1705: rc = sqlite3Select(pParse, pPrior, &uniondest);
! 1706: if( rc ){
! 1707: goto multi_select_end;
! 1708: }
! 1709:
! 1710: /* Code the current SELECT statement
! 1711: */
! 1712: if( p->op==TK_EXCEPT ){
! 1713: op = SRT_Except;
! 1714: }else{
! 1715: assert( p->op==TK_UNION );
! 1716: op = SRT_Union;
! 1717: }
! 1718: p->pPrior = 0;
! 1719: pLimit = p->pLimit;
! 1720: p->pLimit = 0;
! 1721: pOffset = p->pOffset;
! 1722: p->pOffset = 0;
! 1723: uniondest.eDest = op;
! 1724: explainSetInteger(iSub2, pParse->iNextSelectId);
! 1725: rc = sqlite3Select(pParse, p, &uniondest);
! 1726: testcase( rc!=SQLITE_OK );
! 1727: /* Query flattening in sqlite3Select() might refill p->pOrderBy.
! 1728: ** Be sure to delete p->pOrderBy, therefore, to avoid a memory leak. */
! 1729: sqlite3ExprListDelete(db, p->pOrderBy);
! 1730: pDelete = p->pPrior;
! 1731: p->pPrior = pPrior;
! 1732: p->pOrderBy = 0;
! 1733: if( p->op==TK_UNION ) p->nSelectRow += pPrior->nSelectRow;
! 1734: sqlite3ExprDelete(db, p->pLimit);
! 1735: p->pLimit = pLimit;
! 1736: p->pOffset = pOffset;
! 1737: p->iLimit = 0;
! 1738: p->iOffset = 0;
! 1739:
! 1740: /* Convert the data in the temporary table into whatever form
! 1741: ** it is that we currently need.
! 1742: */
! 1743: assert( unionTab==dest.iParm || dest.eDest!=priorOp );
! 1744: if( dest.eDest!=priorOp ){
! 1745: int iCont, iBreak, iStart;
! 1746: assert( p->pEList );
! 1747: if( dest.eDest==SRT_Output ){
! 1748: Select *pFirst = p;
! 1749: while( pFirst->pPrior ) pFirst = pFirst->pPrior;
! 1750: generateColumnNames(pParse, 0, pFirst->pEList);
! 1751: }
! 1752: iBreak = sqlite3VdbeMakeLabel(v);
! 1753: iCont = sqlite3VdbeMakeLabel(v);
! 1754: computeLimitRegisters(pParse, p, iBreak);
! 1755: sqlite3VdbeAddOp2(v, OP_Rewind, unionTab, iBreak);
! 1756: iStart = sqlite3VdbeCurrentAddr(v);
! 1757: selectInnerLoop(pParse, p, p->pEList, unionTab, p->pEList->nExpr,
! 1758: 0, -1, &dest, iCont, iBreak);
! 1759: sqlite3VdbeResolveLabel(v, iCont);
! 1760: sqlite3VdbeAddOp2(v, OP_Next, unionTab, iStart);
! 1761: sqlite3VdbeResolveLabel(v, iBreak);
! 1762: sqlite3VdbeAddOp2(v, OP_Close, unionTab, 0);
! 1763: }
! 1764: break;
! 1765: }
! 1766: default: assert( p->op==TK_INTERSECT ); {
! 1767: int tab1, tab2;
! 1768: int iCont, iBreak, iStart;
! 1769: Expr *pLimit, *pOffset;
! 1770: int addr;
! 1771: SelectDest intersectdest;
! 1772: int r1;
! 1773:
! 1774: /* INTERSECT is different from the others since it requires
! 1775: ** two temporary tables. Hence it has its own case. Begin
! 1776: ** by allocating the tables we will need.
! 1777: */
! 1778: tab1 = pParse->nTab++;
! 1779: tab2 = pParse->nTab++;
! 1780: assert( p->pOrderBy==0 );
! 1781:
! 1782: addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab1, 0);
! 1783: assert( p->addrOpenEphm[0] == -1 );
! 1784: p->addrOpenEphm[0] = addr;
! 1785: p->pRightmost->selFlags |= SF_UsesEphemeral;
! 1786: assert( p->pEList );
! 1787:
! 1788: /* Code the SELECTs to our left into temporary table "tab1".
! 1789: */
! 1790: sqlite3SelectDestInit(&intersectdest, SRT_Union, tab1);
! 1791: explainSetInteger(iSub1, pParse->iNextSelectId);
! 1792: rc = sqlite3Select(pParse, pPrior, &intersectdest);
! 1793: if( rc ){
! 1794: goto multi_select_end;
! 1795: }
! 1796:
! 1797: /* Code the current SELECT into temporary table "tab2"
! 1798: */
! 1799: addr = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tab2, 0);
! 1800: assert( p->addrOpenEphm[1] == -1 );
! 1801: p->addrOpenEphm[1] = addr;
! 1802: p->pPrior = 0;
! 1803: pLimit = p->pLimit;
! 1804: p->pLimit = 0;
! 1805: pOffset = p->pOffset;
! 1806: p->pOffset = 0;
! 1807: intersectdest.iParm = tab2;
! 1808: explainSetInteger(iSub2, pParse->iNextSelectId);
! 1809: rc = sqlite3Select(pParse, p, &intersectdest);
! 1810: testcase( rc!=SQLITE_OK );
! 1811: pDelete = p->pPrior;
! 1812: p->pPrior = pPrior;
! 1813: if( p->nSelectRow>pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow;
! 1814: sqlite3ExprDelete(db, p->pLimit);
! 1815: p->pLimit = pLimit;
! 1816: p->pOffset = pOffset;
! 1817:
! 1818: /* Generate code to take the intersection of the two temporary
! 1819: ** tables.
! 1820: */
! 1821: assert( p->pEList );
! 1822: if( dest.eDest==SRT_Output ){
! 1823: Select *pFirst = p;
! 1824: while( pFirst->pPrior ) pFirst = pFirst->pPrior;
! 1825: generateColumnNames(pParse, 0, pFirst->pEList);
! 1826: }
! 1827: iBreak = sqlite3VdbeMakeLabel(v);
! 1828: iCont = sqlite3VdbeMakeLabel(v);
! 1829: computeLimitRegisters(pParse, p, iBreak);
! 1830: sqlite3VdbeAddOp2(v, OP_Rewind, tab1, iBreak);
! 1831: r1 = sqlite3GetTempReg(pParse);
! 1832: iStart = sqlite3VdbeAddOp2(v, OP_RowKey, tab1, r1);
! 1833: sqlite3VdbeAddOp4Int(v, OP_NotFound, tab2, iCont, r1, 0);
! 1834: sqlite3ReleaseTempReg(pParse, r1);
! 1835: selectInnerLoop(pParse, p, p->pEList, tab1, p->pEList->nExpr,
! 1836: 0, -1, &dest, iCont, iBreak);
! 1837: sqlite3VdbeResolveLabel(v, iCont);
! 1838: sqlite3VdbeAddOp2(v, OP_Next, tab1, iStart);
! 1839: sqlite3VdbeResolveLabel(v, iBreak);
! 1840: sqlite3VdbeAddOp2(v, OP_Close, tab2, 0);
! 1841: sqlite3VdbeAddOp2(v, OP_Close, tab1, 0);
! 1842: break;
! 1843: }
! 1844: }
! 1845:
! 1846: explainComposite(pParse, p->op, iSub1, iSub2, p->op!=TK_ALL);
! 1847:
! 1848: /* Compute collating sequences used by
! 1849: ** temporary tables needed to implement the compound select.
! 1850: ** Attach the KeyInfo structure to all temporary tables.
! 1851: **
! 1852: ** This section is run by the right-most SELECT statement only.
! 1853: ** SELECT statements to the left always skip this part. The right-most
! 1854: ** SELECT might also skip this part if it has no ORDER BY clause and
! 1855: ** no temp tables are required.
! 1856: */
! 1857: if( p->selFlags & SF_UsesEphemeral ){
! 1858: int i; /* Loop counter */
! 1859: KeyInfo *pKeyInfo; /* Collating sequence for the result set */
! 1860: Select *pLoop; /* For looping through SELECT statements */
! 1861: CollSeq **apColl; /* For looping through pKeyInfo->aColl[] */
! 1862: int nCol; /* Number of columns in result set */
! 1863:
! 1864: assert( p->pRightmost==p );
! 1865: nCol = p->pEList->nExpr;
! 1866: pKeyInfo = sqlite3DbMallocZero(db,
! 1867: sizeof(*pKeyInfo)+nCol*(sizeof(CollSeq*) + 1));
! 1868: if( !pKeyInfo ){
! 1869: rc = SQLITE_NOMEM;
! 1870: goto multi_select_end;
! 1871: }
! 1872:
! 1873: pKeyInfo->enc = ENC(db);
! 1874: pKeyInfo->nField = (u16)nCol;
! 1875:
! 1876: for(i=0, apColl=pKeyInfo->aColl; i<nCol; i++, apColl++){
! 1877: *apColl = multiSelectCollSeq(pParse, p, i);
! 1878: if( 0==*apColl ){
! 1879: *apColl = db->pDfltColl;
! 1880: }
! 1881: }
! 1882:
! 1883: for(pLoop=p; pLoop; pLoop=pLoop->pPrior){
! 1884: for(i=0; i<2; i++){
! 1885: int addr = pLoop->addrOpenEphm[i];
! 1886: if( addr<0 ){
! 1887: /* If [0] is unused then [1] is also unused. So we can
! 1888: ** always safely abort as soon as the first unused slot is found */
! 1889: assert( pLoop->addrOpenEphm[1]<0 );
! 1890: break;
! 1891: }
! 1892: sqlite3VdbeChangeP2(v, addr, nCol);
! 1893: sqlite3VdbeChangeP4(v, addr, (char*)pKeyInfo, P4_KEYINFO);
! 1894: pLoop->addrOpenEphm[i] = -1;
! 1895: }
! 1896: }
! 1897: sqlite3DbFree(db, pKeyInfo);
! 1898: }
! 1899:
! 1900: multi_select_end:
! 1901: pDest->iMem = dest.iMem;
! 1902: pDest->nMem = dest.nMem;
! 1903: sqlite3SelectDelete(db, pDelete);
! 1904: return rc;
! 1905: }
! 1906: #endif /* SQLITE_OMIT_COMPOUND_SELECT */
! 1907:
! 1908: /*
! 1909: ** Code an output subroutine for a coroutine implementation of a
! 1910: ** SELECT statment.
! 1911: **
! 1912: ** The data to be output is contained in pIn->iMem. There are
! 1913: ** pIn->nMem columns to be output. pDest is where the output should
! 1914: ** be sent.
! 1915: **
! 1916: ** regReturn is the number of the register holding the subroutine
! 1917: ** return address.
! 1918: **
! 1919: ** If regPrev>0 then it is the first register in a vector that
! 1920: ** records the previous output. mem[regPrev] is a flag that is false
! 1921: ** if there has been no previous output. If regPrev>0 then code is
! 1922: ** generated to suppress duplicates. pKeyInfo is used for comparing
! 1923: ** keys.
! 1924: **
! 1925: ** If the LIMIT found in p->iLimit is reached, jump immediately to
! 1926: ** iBreak.
! 1927: */
! 1928: static int generateOutputSubroutine(
! 1929: Parse *pParse, /* Parsing context */
! 1930: Select *p, /* The SELECT statement */
! 1931: SelectDest *pIn, /* Coroutine supplying data */
! 1932: SelectDest *pDest, /* Where to send the data */
! 1933: int regReturn, /* The return address register */
! 1934: int regPrev, /* Previous result register. No uniqueness if 0 */
! 1935: KeyInfo *pKeyInfo, /* For comparing with previous entry */
! 1936: int p4type, /* The p4 type for pKeyInfo */
! 1937: int iBreak /* Jump here if we hit the LIMIT */
! 1938: ){
! 1939: Vdbe *v = pParse->pVdbe;
! 1940: int iContinue;
! 1941: int addr;
! 1942:
! 1943: addr = sqlite3VdbeCurrentAddr(v);
! 1944: iContinue = sqlite3VdbeMakeLabel(v);
! 1945:
! 1946: /* Suppress duplicates for UNION, EXCEPT, and INTERSECT
! 1947: */
! 1948: if( regPrev ){
! 1949: int j1, j2;
! 1950: j1 = sqlite3VdbeAddOp1(v, OP_IfNot, regPrev);
! 1951: j2 = sqlite3VdbeAddOp4(v, OP_Compare, pIn->iMem, regPrev+1, pIn->nMem,
! 1952: (char*)pKeyInfo, p4type);
! 1953: sqlite3VdbeAddOp3(v, OP_Jump, j2+2, iContinue, j2+2);
! 1954: sqlite3VdbeJumpHere(v, j1);
! 1955: sqlite3ExprCodeCopy(pParse, pIn->iMem, regPrev+1, pIn->nMem);
! 1956: sqlite3VdbeAddOp2(v, OP_Integer, 1, regPrev);
! 1957: }
! 1958: if( pParse->db->mallocFailed ) return 0;
! 1959:
! 1960: /* Suppress the the first OFFSET entries if there is an OFFSET clause
! 1961: */
! 1962: codeOffset(v, p, iContinue);
! 1963:
! 1964: switch( pDest->eDest ){
! 1965: /* Store the result as data using a unique key.
! 1966: */
! 1967: case SRT_Table:
! 1968: case SRT_EphemTab: {
! 1969: int r1 = sqlite3GetTempReg(pParse);
! 1970: int r2 = sqlite3GetTempReg(pParse);
! 1971: testcase( pDest->eDest==SRT_Table );
! 1972: testcase( pDest->eDest==SRT_EphemTab );
! 1973: sqlite3VdbeAddOp3(v, OP_MakeRecord, pIn->iMem, pIn->nMem, r1);
! 1974: sqlite3VdbeAddOp2(v, OP_NewRowid, pDest->iParm, r2);
! 1975: sqlite3VdbeAddOp3(v, OP_Insert, pDest->iParm, r1, r2);
! 1976: sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
! 1977: sqlite3ReleaseTempReg(pParse, r2);
! 1978: sqlite3ReleaseTempReg(pParse, r1);
! 1979: break;
! 1980: }
! 1981:
! 1982: #ifndef SQLITE_OMIT_SUBQUERY
! 1983: /* If we are creating a set for an "expr IN (SELECT ...)" construct,
! 1984: ** then there should be a single item on the stack. Write this
! 1985: ** item into the set table with bogus data.
! 1986: */
! 1987: case SRT_Set: {
! 1988: int r1;
! 1989: assert( pIn->nMem==1 );
! 1990: p->affinity =
! 1991: sqlite3CompareAffinity(p->pEList->a[0].pExpr, pDest->affinity);
! 1992: r1 = sqlite3GetTempReg(pParse);
! 1993: sqlite3VdbeAddOp4(v, OP_MakeRecord, pIn->iMem, 1, r1, &p->affinity, 1);
! 1994: sqlite3ExprCacheAffinityChange(pParse, pIn->iMem, 1);
! 1995: sqlite3VdbeAddOp2(v, OP_IdxInsert, pDest->iParm, r1);
! 1996: sqlite3ReleaseTempReg(pParse, r1);
! 1997: break;
! 1998: }
! 1999:
! 2000: #if 0 /* Never occurs on an ORDER BY query */
! 2001: /* If any row exist in the result set, record that fact and abort.
! 2002: */
! 2003: case SRT_Exists: {
! 2004: sqlite3VdbeAddOp2(v, OP_Integer, 1, pDest->iParm);
! 2005: /* The LIMIT clause will terminate the loop for us */
! 2006: break;
! 2007: }
! 2008: #endif
! 2009:
! 2010: /* If this is a scalar select that is part of an expression, then
! 2011: ** store the results in the appropriate memory cell and break out
! 2012: ** of the scan loop.
! 2013: */
! 2014: case SRT_Mem: {
! 2015: assert( pIn->nMem==1 );
! 2016: sqlite3ExprCodeMove(pParse, pIn->iMem, pDest->iParm, 1);
! 2017: /* The LIMIT clause will jump out of the loop for us */
! 2018: break;
! 2019: }
! 2020: #endif /* #ifndef SQLITE_OMIT_SUBQUERY */
! 2021:
! 2022: /* The results are stored in a sequence of registers
! 2023: ** starting at pDest->iMem. Then the co-routine yields.
! 2024: */
! 2025: case SRT_Coroutine: {
! 2026: if( pDest->iMem==0 ){
! 2027: pDest->iMem = sqlite3GetTempRange(pParse, pIn->nMem);
! 2028: pDest->nMem = pIn->nMem;
! 2029: }
! 2030: sqlite3ExprCodeMove(pParse, pIn->iMem, pDest->iMem, pDest->nMem);
! 2031: sqlite3VdbeAddOp1(v, OP_Yield, pDest->iParm);
! 2032: break;
! 2033: }
! 2034:
! 2035: /* If none of the above, then the result destination must be
! 2036: ** SRT_Output. This routine is never called with any other
! 2037: ** destination other than the ones handled above or SRT_Output.
! 2038: **
! 2039: ** For SRT_Output, results are stored in a sequence of registers.
! 2040: ** Then the OP_ResultRow opcode is used to cause sqlite3_step() to
! 2041: ** return the next row of result.
! 2042: */
! 2043: default: {
! 2044: assert( pDest->eDest==SRT_Output );
! 2045: sqlite3VdbeAddOp2(v, OP_ResultRow, pIn->iMem, pIn->nMem);
! 2046: sqlite3ExprCacheAffinityChange(pParse, pIn->iMem, pIn->nMem);
! 2047: break;
! 2048: }
! 2049: }
! 2050:
! 2051: /* Jump to the end of the loop if the LIMIT is reached.
! 2052: */
! 2053: if( p->iLimit ){
! 2054: sqlite3VdbeAddOp3(v, OP_IfZero, p->iLimit, iBreak, -1);
! 2055: }
! 2056:
! 2057: /* Generate the subroutine return
! 2058: */
! 2059: sqlite3VdbeResolveLabel(v, iContinue);
! 2060: sqlite3VdbeAddOp1(v, OP_Return, regReturn);
! 2061:
! 2062: return addr;
! 2063: }
! 2064:
! 2065: /*
! 2066: ** Alternative compound select code generator for cases when there
! 2067: ** is an ORDER BY clause.
! 2068: **
! 2069: ** We assume a query of the following form:
! 2070: **
! 2071: ** <selectA> <operator> <selectB> ORDER BY <orderbylist>
! 2072: **
! 2073: ** <operator> is one of UNION ALL, UNION, EXCEPT, or INTERSECT. The idea
! 2074: ** is to code both <selectA> and <selectB> with the ORDER BY clause as
! 2075: ** co-routines. Then run the co-routines in parallel and merge the results
! 2076: ** into the output. In addition to the two coroutines (called selectA and
! 2077: ** selectB) there are 7 subroutines:
! 2078: **
! 2079: ** outA: Move the output of the selectA coroutine into the output
! 2080: ** of the compound query.
! 2081: **
! 2082: ** outB: Move the output of the selectB coroutine into the output
! 2083: ** of the compound query. (Only generated for UNION and
! 2084: ** UNION ALL. EXCEPT and INSERTSECT never output a row that
! 2085: ** appears only in B.)
! 2086: **
! 2087: ** AltB: Called when there is data from both coroutines and A<B.
! 2088: **
! 2089: ** AeqB: Called when there is data from both coroutines and A==B.
! 2090: **
! 2091: ** AgtB: Called when there is data from both coroutines and A>B.
! 2092: **
! 2093: ** EofA: Called when data is exhausted from selectA.
! 2094: **
! 2095: ** EofB: Called when data is exhausted from selectB.
! 2096: **
! 2097: ** The implementation of the latter five subroutines depend on which
! 2098: ** <operator> is used:
! 2099: **
! 2100: **
! 2101: ** UNION ALL UNION EXCEPT INTERSECT
! 2102: ** ------------- ----------------- -------------- -----------------
! 2103: ** AltB: outA, nextA outA, nextA outA, nextA nextA
! 2104: **
! 2105: ** AeqB: outA, nextA nextA nextA outA, nextA
! 2106: **
! 2107: ** AgtB: outB, nextB outB, nextB nextB nextB
! 2108: **
! 2109: ** EofA: outB, nextB outB, nextB halt halt
! 2110: **
! 2111: ** EofB: outA, nextA outA, nextA outA, nextA halt
! 2112: **
! 2113: ** In the AltB, AeqB, and AgtB subroutines, an EOF on A following nextA
! 2114: ** causes an immediate jump to EofA and an EOF on B following nextB causes
! 2115: ** an immediate jump to EofB. Within EofA and EofB, and EOF on entry or
! 2116: ** following nextX causes a jump to the end of the select processing.
! 2117: **
! 2118: ** Duplicate removal in the UNION, EXCEPT, and INTERSECT cases is handled
! 2119: ** within the output subroutine. The regPrev register set holds the previously
! 2120: ** output value. A comparison is made against this value and the output
! 2121: ** is skipped if the next results would be the same as the previous.
! 2122: **
! 2123: ** The implementation plan is to implement the two coroutines and seven
! 2124: ** subroutines first, then put the control logic at the bottom. Like this:
! 2125: **
! 2126: ** goto Init
! 2127: ** coA: coroutine for left query (A)
! 2128: ** coB: coroutine for right query (B)
! 2129: ** outA: output one row of A
! 2130: ** outB: output one row of B (UNION and UNION ALL only)
! 2131: ** EofA: ...
! 2132: ** EofB: ...
! 2133: ** AltB: ...
! 2134: ** AeqB: ...
! 2135: ** AgtB: ...
! 2136: ** Init: initialize coroutine registers
! 2137: ** yield coA
! 2138: ** if eof(A) goto EofA
! 2139: ** yield coB
! 2140: ** if eof(B) goto EofB
! 2141: ** Cmpr: Compare A, B
! 2142: ** Jump AltB, AeqB, AgtB
! 2143: ** End: ...
! 2144: **
! 2145: ** We call AltB, AeqB, AgtB, EofA, and EofB "subroutines" but they are not
! 2146: ** actually called using Gosub and they do not Return. EofA and EofB loop
! 2147: ** until all data is exhausted then jump to the "end" labe. AltB, AeqB,
! 2148: ** and AgtB jump to either L2 or to one of EofA or EofB.
! 2149: */
! 2150: #ifndef SQLITE_OMIT_COMPOUND_SELECT
! 2151: static int multiSelectOrderBy(
! 2152: Parse *pParse, /* Parsing context */
! 2153: Select *p, /* The right-most of SELECTs to be coded */
! 2154: SelectDest *pDest /* What to do with query results */
! 2155: ){
! 2156: int i, j; /* Loop counters */
! 2157: Select *pPrior; /* Another SELECT immediately to our left */
! 2158: Vdbe *v; /* Generate code to this VDBE */
! 2159: SelectDest destA; /* Destination for coroutine A */
! 2160: SelectDest destB; /* Destination for coroutine B */
! 2161: int regAddrA; /* Address register for select-A coroutine */
! 2162: int regEofA; /* Flag to indicate when select-A is complete */
! 2163: int regAddrB; /* Address register for select-B coroutine */
! 2164: int regEofB; /* Flag to indicate when select-B is complete */
! 2165: int addrSelectA; /* Address of the select-A coroutine */
! 2166: int addrSelectB; /* Address of the select-B coroutine */
! 2167: int regOutA; /* Address register for the output-A subroutine */
! 2168: int regOutB; /* Address register for the output-B subroutine */
! 2169: int addrOutA; /* Address of the output-A subroutine */
! 2170: int addrOutB = 0; /* Address of the output-B subroutine */
! 2171: int addrEofA; /* Address of the select-A-exhausted subroutine */
! 2172: int addrEofB; /* Address of the select-B-exhausted subroutine */
! 2173: int addrAltB; /* Address of the A<B subroutine */
! 2174: int addrAeqB; /* Address of the A==B subroutine */
! 2175: int addrAgtB; /* Address of the A>B subroutine */
! 2176: int regLimitA; /* Limit register for select-A */
! 2177: int regLimitB; /* Limit register for select-A */
! 2178: int regPrev; /* A range of registers to hold previous output */
! 2179: int savedLimit; /* Saved value of p->iLimit */
! 2180: int savedOffset; /* Saved value of p->iOffset */
! 2181: int labelCmpr; /* Label for the start of the merge algorithm */
! 2182: int labelEnd; /* Label for the end of the overall SELECT stmt */
! 2183: int j1; /* Jump instructions that get retargetted */
! 2184: int op; /* One of TK_ALL, TK_UNION, TK_EXCEPT, TK_INTERSECT */
! 2185: KeyInfo *pKeyDup = 0; /* Comparison information for duplicate removal */
! 2186: KeyInfo *pKeyMerge; /* Comparison information for merging rows */
! 2187: sqlite3 *db; /* Database connection */
! 2188: ExprList *pOrderBy; /* The ORDER BY clause */
! 2189: int nOrderBy; /* Number of terms in the ORDER BY clause */
! 2190: int *aPermute; /* Mapping from ORDER BY terms to result set columns */
! 2191: #ifndef SQLITE_OMIT_EXPLAIN
! 2192: int iSub1; /* EQP id of left-hand query */
! 2193: int iSub2; /* EQP id of right-hand query */
! 2194: #endif
! 2195:
! 2196: assert( p->pOrderBy!=0 );
! 2197: assert( pKeyDup==0 ); /* "Managed" code needs this. Ticket #3382. */
! 2198: db = pParse->db;
! 2199: v = pParse->pVdbe;
! 2200: assert( v!=0 ); /* Already thrown the error if VDBE alloc failed */
! 2201: labelEnd = sqlite3VdbeMakeLabel(v);
! 2202: labelCmpr = sqlite3VdbeMakeLabel(v);
! 2203:
! 2204:
! 2205: /* Patch up the ORDER BY clause
! 2206: */
! 2207: op = p->op;
! 2208: pPrior = p->pPrior;
! 2209: assert( pPrior->pOrderBy==0 );
! 2210: pOrderBy = p->pOrderBy;
! 2211: assert( pOrderBy );
! 2212: nOrderBy = pOrderBy->nExpr;
! 2213:
! 2214: /* For operators other than UNION ALL we have to make sure that
! 2215: ** the ORDER BY clause covers every term of the result set. Add
! 2216: ** terms to the ORDER BY clause as necessary.
! 2217: */
! 2218: if( op!=TK_ALL ){
! 2219: for(i=1; db->mallocFailed==0 && i<=p->pEList->nExpr; i++){
! 2220: struct ExprList_item *pItem;
! 2221: for(j=0, pItem=pOrderBy->a; j<nOrderBy; j++, pItem++){
! 2222: assert( pItem->iOrderByCol>0 );
! 2223: if( pItem->iOrderByCol==i ) break;
! 2224: }
! 2225: if( j==nOrderBy ){
! 2226: Expr *pNew = sqlite3Expr(db, TK_INTEGER, 0);
! 2227: if( pNew==0 ) return SQLITE_NOMEM;
! 2228: pNew->flags |= EP_IntValue;
! 2229: pNew->u.iValue = i;
! 2230: pOrderBy = sqlite3ExprListAppend(pParse, pOrderBy, pNew);
! 2231: pOrderBy->a[nOrderBy++].iOrderByCol = (u16)i;
! 2232: }
! 2233: }
! 2234: }
! 2235:
! 2236: /* Compute the comparison permutation and keyinfo that is used with
! 2237: ** the permutation used to determine if the next
! 2238: ** row of results comes from selectA or selectB. Also add explicit
! 2239: ** collations to the ORDER BY clause terms so that when the subqueries
! 2240: ** to the right and the left are evaluated, they use the correct
! 2241: ** collation.
! 2242: */
! 2243: aPermute = sqlite3DbMallocRaw(db, sizeof(int)*nOrderBy);
! 2244: if( aPermute ){
! 2245: struct ExprList_item *pItem;
! 2246: for(i=0, pItem=pOrderBy->a; i<nOrderBy; i++, pItem++){
! 2247: assert( pItem->iOrderByCol>0 && pItem->iOrderByCol<=p->pEList->nExpr );
! 2248: aPermute[i] = pItem->iOrderByCol - 1;
! 2249: }
! 2250: pKeyMerge =
! 2251: sqlite3DbMallocRaw(db, sizeof(*pKeyMerge)+nOrderBy*(sizeof(CollSeq*)+1));
! 2252: if( pKeyMerge ){
! 2253: pKeyMerge->aSortOrder = (u8*)&pKeyMerge->aColl[nOrderBy];
! 2254: pKeyMerge->nField = (u16)nOrderBy;
! 2255: pKeyMerge->enc = ENC(db);
! 2256: for(i=0; i<nOrderBy; i++){
! 2257: CollSeq *pColl;
! 2258: Expr *pTerm = pOrderBy->a[i].pExpr;
! 2259: if( pTerm->flags & EP_ExpCollate ){
! 2260: pColl = pTerm->pColl;
! 2261: }else{
! 2262: pColl = multiSelectCollSeq(pParse, p, aPermute[i]);
! 2263: pTerm->flags |= EP_ExpCollate;
! 2264: pTerm->pColl = pColl;
! 2265: }
! 2266: pKeyMerge->aColl[i] = pColl;
! 2267: pKeyMerge->aSortOrder[i] = pOrderBy->a[i].sortOrder;
! 2268: }
! 2269: }
! 2270: }else{
! 2271: pKeyMerge = 0;
! 2272: }
! 2273:
! 2274: /* Reattach the ORDER BY clause to the query.
! 2275: */
! 2276: p->pOrderBy = pOrderBy;
! 2277: pPrior->pOrderBy = sqlite3ExprListDup(pParse->db, pOrderBy, 0);
! 2278:
! 2279: /* Allocate a range of temporary registers and the KeyInfo needed
! 2280: ** for the logic that removes duplicate result rows when the
! 2281: ** operator is UNION, EXCEPT, or INTERSECT (but not UNION ALL).
! 2282: */
! 2283: if( op==TK_ALL ){
! 2284: regPrev = 0;
! 2285: }else{
! 2286: int nExpr = p->pEList->nExpr;
! 2287: assert( nOrderBy>=nExpr || db->mallocFailed );
! 2288: regPrev = sqlite3GetTempRange(pParse, nExpr+1);
! 2289: sqlite3VdbeAddOp2(v, OP_Integer, 0, regPrev);
! 2290: pKeyDup = sqlite3DbMallocZero(db,
! 2291: sizeof(*pKeyDup) + nExpr*(sizeof(CollSeq*)+1) );
! 2292: if( pKeyDup ){
! 2293: pKeyDup->aSortOrder = (u8*)&pKeyDup->aColl[nExpr];
! 2294: pKeyDup->nField = (u16)nExpr;
! 2295: pKeyDup->enc = ENC(db);
! 2296: for(i=0; i<nExpr; i++){
! 2297: pKeyDup->aColl[i] = multiSelectCollSeq(pParse, p, i);
! 2298: pKeyDup->aSortOrder[i] = 0;
! 2299: }
! 2300: }
! 2301: }
! 2302:
! 2303: /* Separate the left and the right query from one another
! 2304: */
! 2305: p->pPrior = 0;
! 2306: sqlite3ResolveOrderGroupBy(pParse, p, p->pOrderBy, "ORDER");
! 2307: if( pPrior->pPrior==0 ){
! 2308: sqlite3ResolveOrderGroupBy(pParse, pPrior, pPrior->pOrderBy, "ORDER");
! 2309: }
! 2310:
! 2311: /* Compute the limit registers */
! 2312: computeLimitRegisters(pParse, p, labelEnd);
! 2313: if( p->iLimit && op==TK_ALL ){
! 2314: regLimitA = ++pParse->nMem;
! 2315: regLimitB = ++pParse->nMem;
! 2316: sqlite3VdbeAddOp2(v, OP_Copy, p->iOffset ? p->iOffset+1 : p->iLimit,
! 2317: regLimitA);
! 2318: sqlite3VdbeAddOp2(v, OP_Copy, regLimitA, regLimitB);
! 2319: }else{
! 2320: regLimitA = regLimitB = 0;
! 2321: }
! 2322: sqlite3ExprDelete(db, p->pLimit);
! 2323: p->pLimit = 0;
! 2324: sqlite3ExprDelete(db, p->pOffset);
! 2325: p->pOffset = 0;
! 2326:
! 2327: regAddrA = ++pParse->nMem;
! 2328: regEofA = ++pParse->nMem;
! 2329: regAddrB = ++pParse->nMem;
! 2330: regEofB = ++pParse->nMem;
! 2331: regOutA = ++pParse->nMem;
! 2332: regOutB = ++pParse->nMem;
! 2333: sqlite3SelectDestInit(&destA, SRT_Coroutine, regAddrA);
! 2334: sqlite3SelectDestInit(&destB, SRT_Coroutine, regAddrB);
! 2335:
! 2336: /* Jump past the various subroutines and coroutines to the main
! 2337: ** merge loop
! 2338: */
! 2339: j1 = sqlite3VdbeAddOp0(v, OP_Goto);
! 2340: addrSelectA = sqlite3VdbeCurrentAddr(v);
! 2341:
! 2342:
! 2343: /* Generate a coroutine to evaluate the SELECT statement to the
! 2344: ** left of the compound operator - the "A" select.
! 2345: */
! 2346: VdbeNoopComment((v, "Begin coroutine for left SELECT"));
! 2347: pPrior->iLimit = regLimitA;
! 2348: explainSetInteger(iSub1, pParse->iNextSelectId);
! 2349: sqlite3Select(pParse, pPrior, &destA);
! 2350: sqlite3VdbeAddOp2(v, OP_Integer, 1, regEofA);
! 2351: sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
! 2352: VdbeNoopComment((v, "End coroutine for left SELECT"));
! 2353:
! 2354: /* Generate a coroutine to evaluate the SELECT statement on
! 2355: ** the right - the "B" select
! 2356: */
! 2357: addrSelectB = sqlite3VdbeCurrentAddr(v);
! 2358: VdbeNoopComment((v, "Begin coroutine for right SELECT"));
! 2359: savedLimit = p->iLimit;
! 2360: savedOffset = p->iOffset;
! 2361: p->iLimit = regLimitB;
! 2362: p->iOffset = 0;
! 2363: explainSetInteger(iSub2, pParse->iNextSelectId);
! 2364: sqlite3Select(pParse, p, &destB);
! 2365: p->iLimit = savedLimit;
! 2366: p->iOffset = savedOffset;
! 2367: sqlite3VdbeAddOp2(v, OP_Integer, 1, regEofB);
! 2368: sqlite3VdbeAddOp1(v, OP_Yield, regAddrB);
! 2369: VdbeNoopComment((v, "End coroutine for right SELECT"));
! 2370:
! 2371: /* Generate a subroutine that outputs the current row of the A
! 2372: ** select as the next output row of the compound select.
! 2373: */
! 2374: VdbeNoopComment((v, "Output routine for A"));
! 2375: addrOutA = generateOutputSubroutine(pParse,
! 2376: p, &destA, pDest, regOutA,
! 2377: regPrev, pKeyDup, P4_KEYINFO_HANDOFF, labelEnd);
! 2378:
! 2379: /* Generate a subroutine that outputs the current row of the B
! 2380: ** select as the next output row of the compound select.
! 2381: */
! 2382: if( op==TK_ALL || op==TK_UNION ){
! 2383: VdbeNoopComment((v, "Output routine for B"));
! 2384: addrOutB = generateOutputSubroutine(pParse,
! 2385: p, &destB, pDest, regOutB,
! 2386: regPrev, pKeyDup, P4_KEYINFO_STATIC, labelEnd);
! 2387: }
! 2388:
! 2389: /* Generate a subroutine to run when the results from select A
! 2390: ** are exhausted and only data in select B remains.
! 2391: */
! 2392: VdbeNoopComment((v, "eof-A subroutine"));
! 2393: if( op==TK_EXCEPT || op==TK_INTERSECT ){
! 2394: addrEofA = sqlite3VdbeAddOp2(v, OP_Goto, 0, labelEnd);
! 2395: }else{
! 2396: addrEofA = sqlite3VdbeAddOp2(v, OP_If, regEofB, labelEnd);
! 2397: sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
! 2398: sqlite3VdbeAddOp1(v, OP_Yield, regAddrB);
! 2399: sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEofA);
! 2400: p->nSelectRow += pPrior->nSelectRow;
! 2401: }
! 2402:
! 2403: /* Generate a subroutine to run when the results from select B
! 2404: ** are exhausted and only data in select A remains.
! 2405: */
! 2406: if( op==TK_INTERSECT ){
! 2407: addrEofB = addrEofA;
! 2408: if( p->nSelectRow > pPrior->nSelectRow ) p->nSelectRow = pPrior->nSelectRow;
! 2409: }else{
! 2410: VdbeNoopComment((v, "eof-B subroutine"));
! 2411: addrEofB = sqlite3VdbeAddOp2(v, OP_If, regEofA, labelEnd);
! 2412: sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
! 2413: sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
! 2414: sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEofB);
! 2415: }
! 2416:
! 2417: /* Generate code to handle the case of A<B
! 2418: */
! 2419: VdbeNoopComment((v, "A-lt-B subroutine"));
! 2420: addrAltB = sqlite3VdbeAddOp2(v, OP_Gosub, regOutA, addrOutA);
! 2421: sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
! 2422: sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA);
! 2423: sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);
! 2424:
! 2425: /* Generate code to handle the case of A==B
! 2426: */
! 2427: if( op==TK_ALL ){
! 2428: addrAeqB = addrAltB;
! 2429: }else if( op==TK_INTERSECT ){
! 2430: addrAeqB = addrAltB;
! 2431: addrAltB++;
! 2432: }else{
! 2433: VdbeNoopComment((v, "A-eq-B subroutine"));
! 2434: addrAeqB =
! 2435: sqlite3VdbeAddOp1(v, OP_Yield, regAddrA);
! 2436: sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA);
! 2437: sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);
! 2438: }
! 2439:
! 2440: /* Generate code to handle the case of A>B
! 2441: */
! 2442: VdbeNoopComment((v, "A-gt-B subroutine"));
! 2443: addrAgtB = sqlite3VdbeCurrentAddr(v);
! 2444: if( op==TK_ALL || op==TK_UNION ){
! 2445: sqlite3VdbeAddOp2(v, OP_Gosub, regOutB, addrOutB);
! 2446: }
! 2447: sqlite3VdbeAddOp1(v, OP_Yield, regAddrB);
! 2448: sqlite3VdbeAddOp2(v, OP_If, regEofB, addrEofB);
! 2449: sqlite3VdbeAddOp2(v, OP_Goto, 0, labelCmpr);
! 2450:
! 2451: /* This code runs once to initialize everything.
! 2452: */
! 2453: sqlite3VdbeJumpHere(v, j1);
! 2454: sqlite3VdbeAddOp2(v, OP_Integer, 0, regEofA);
! 2455: sqlite3VdbeAddOp2(v, OP_Integer, 0, regEofB);
! 2456: sqlite3VdbeAddOp2(v, OP_Gosub, regAddrA, addrSelectA);
! 2457: sqlite3VdbeAddOp2(v, OP_Gosub, regAddrB, addrSelectB);
! 2458: sqlite3VdbeAddOp2(v, OP_If, regEofA, addrEofA);
! 2459: sqlite3VdbeAddOp2(v, OP_If, regEofB, addrEofB);
! 2460:
! 2461: /* Implement the main merge loop
! 2462: */
! 2463: sqlite3VdbeResolveLabel(v, labelCmpr);
! 2464: sqlite3VdbeAddOp4(v, OP_Permutation, 0, 0, 0, (char*)aPermute, P4_INTARRAY);
! 2465: sqlite3VdbeAddOp4(v, OP_Compare, destA.iMem, destB.iMem, nOrderBy,
! 2466: (char*)pKeyMerge, P4_KEYINFO_HANDOFF);
! 2467: sqlite3VdbeAddOp3(v, OP_Jump, addrAltB, addrAeqB, addrAgtB);
! 2468:
! 2469: /* Release temporary registers
! 2470: */
! 2471: if( regPrev ){
! 2472: sqlite3ReleaseTempRange(pParse, regPrev, nOrderBy+1);
! 2473: }
! 2474:
! 2475: /* Jump to the this point in order to terminate the query.
! 2476: */
! 2477: sqlite3VdbeResolveLabel(v, labelEnd);
! 2478:
! 2479: /* Set the number of output columns
! 2480: */
! 2481: if( pDest->eDest==SRT_Output ){
! 2482: Select *pFirst = pPrior;
! 2483: while( pFirst->pPrior ) pFirst = pFirst->pPrior;
! 2484: generateColumnNames(pParse, 0, pFirst->pEList);
! 2485: }
! 2486:
! 2487: /* Reassembly the compound query so that it will be freed correctly
! 2488: ** by the calling function */
! 2489: if( p->pPrior ){
! 2490: sqlite3SelectDelete(db, p->pPrior);
! 2491: }
! 2492: p->pPrior = pPrior;
! 2493:
! 2494: /*** TBD: Insert subroutine calls to close cursors on incomplete
! 2495: **** subqueries ****/
! 2496: explainComposite(pParse, p->op, iSub1, iSub2, 0);
! 2497: return SQLITE_OK;
! 2498: }
! 2499: #endif
! 2500:
! 2501: #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
! 2502: /* Forward Declarations */
! 2503: static void substExprList(sqlite3*, ExprList*, int, ExprList*);
! 2504: static void substSelect(sqlite3*, Select *, int, ExprList *);
! 2505:
! 2506: /*
! 2507: ** Scan through the expression pExpr. Replace every reference to
! 2508: ** a column in table number iTable with a copy of the iColumn-th
! 2509: ** entry in pEList. (But leave references to the ROWID column
! 2510: ** unchanged.)
! 2511: **
! 2512: ** This routine is part of the flattening procedure. A subquery
! 2513: ** whose result set is defined by pEList appears as entry in the
! 2514: ** FROM clause of a SELECT such that the VDBE cursor assigned to that
! 2515: ** FORM clause entry is iTable. This routine make the necessary
! 2516: ** changes to pExpr so that it refers directly to the source table
! 2517: ** of the subquery rather the result set of the subquery.
! 2518: */
! 2519: static Expr *substExpr(
! 2520: sqlite3 *db, /* Report malloc errors to this connection */
! 2521: Expr *pExpr, /* Expr in which substitution occurs */
! 2522: int iTable, /* Table to be substituted */
! 2523: ExprList *pEList /* Substitute expressions */
! 2524: ){
! 2525: if( pExpr==0 ) return 0;
! 2526: if( pExpr->op==TK_COLUMN && pExpr->iTable==iTable ){
! 2527: if( pExpr->iColumn<0 ){
! 2528: pExpr->op = TK_NULL;
! 2529: }else{
! 2530: Expr *pNew;
! 2531: assert( pEList!=0 && pExpr->iColumn<pEList->nExpr );
! 2532: assert( pExpr->pLeft==0 && pExpr->pRight==0 );
! 2533: pNew = sqlite3ExprDup(db, pEList->a[pExpr->iColumn].pExpr, 0);
! 2534: if( pNew && pExpr->pColl ){
! 2535: pNew->pColl = pExpr->pColl;
! 2536: }
! 2537: sqlite3ExprDelete(db, pExpr);
! 2538: pExpr = pNew;
! 2539: }
! 2540: }else{
! 2541: pExpr->pLeft = substExpr(db, pExpr->pLeft, iTable, pEList);
! 2542: pExpr->pRight = substExpr(db, pExpr->pRight, iTable, pEList);
! 2543: if( ExprHasProperty(pExpr, EP_xIsSelect) ){
! 2544: substSelect(db, pExpr->x.pSelect, iTable, pEList);
! 2545: }else{
! 2546: substExprList(db, pExpr->x.pList, iTable, pEList);
! 2547: }
! 2548: }
! 2549: return pExpr;
! 2550: }
! 2551: static void substExprList(
! 2552: sqlite3 *db, /* Report malloc errors here */
! 2553: ExprList *pList, /* List to scan and in which to make substitutes */
! 2554: int iTable, /* Table to be substituted */
! 2555: ExprList *pEList /* Substitute values */
! 2556: ){
! 2557: int i;
! 2558: if( pList==0 ) return;
! 2559: for(i=0; i<pList->nExpr; i++){
! 2560: pList->a[i].pExpr = substExpr(db, pList->a[i].pExpr, iTable, pEList);
! 2561: }
! 2562: }
! 2563: static void substSelect(
! 2564: sqlite3 *db, /* Report malloc errors here */
! 2565: Select *p, /* SELECT statement in which to make substitutions */
! 2566: int iTable, /* Table to be replaced */
! 2567: ExprList *pEList /* Substitute values */
! 2568: ){
! 2569: SrcList *pSrc;
! 2570: struct SrcList_item *pItem;
! 2571: int i;
! 2572: if( !p ) return;
! 2573: substExprList(db, p->pEList, iTable, pEList);
! 2574: substExprList(db, p->pGroupBy, iTable, pEList);
! 2575: substExprList(db, p->pOrderBy, iTable, pEList);
! 2576: p->pHaving = substExpr(db, p->pHaving, iTable, pEList);
! 2577: p->pWhere = substExpr(db, p->pWhere, iTable, pEList);
! 2578: substSelect(db, p->pPrior, iTable, pEList);
! 2579: pSrc = p->pSrc;
! 2580: assert( pSrc ); /* Even for (SELECT 1) we have: pSrc!=0 but pSrc->nSrc==0 */
! 2581: if( ALWAYS(pSrc) ){
! 2582: for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
! 2583: substSelect(db, pItem->pSelect, iTable, pEList);
! 2584: }
! 2585: }
! 2586: }
! 2587: #endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
! 2588:
! 2589: #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
! 2590: /*
! 2591: ** This routine attempts to flatten subqueries as a performance optimization.
! 2592: ** This routine returns 1 if it makes changes and 0 if no flattening occurs.
! 2593: **
! 2594: ** To understand the concept of flattening, consider the following
! 2595: ** query:
! 2596: **
! 2597: ** SELECT a FROM (SELECT x+y AS a FROM t1 WHERE z<100) WHERE a>5
! 2598: **
! 2599: ** The default way of implementing this query is to execute the
! 2600: ** subquery first and store the results in a temporary table, then
! 2601: ** run the outer query on that temporary table. This requires two
! 2602: ** passes over the data. Furthermore, because the temporary table
! 2603: ** has no indices, the WHERE clause on the outer query cannot be
! 2604: ** optimized.
! 2605: **
! 2606: ** This routine attempts to rewrite queries such as the above into
! 2607: ** a single flat select, like this:
! 2608: **
! 2609: ** SELECT x+y AS a FROM t1 WHERE z<100 AND a>5
! 2610: **
! 2611: ** The code generated for this simpification gives the same result
! 2612: ** but only has to scan the data once. And because indices might
! 2613: ** exist on the table t1, a complete scan of the data might be
! 2614: ** avoided.
! 2615: **
! 2616: ** Flattening is only attempted if all of the following are true:
! 2617: **
! 2618: ** (1) The subquery and the outer query do not both use aggregates.
! 2619: **
! 2620: ** (2) The subquery is not an aggregate or the outer query is not a join.
! 2621: **
! 2622: ** (3) The subquery is not the right operand of a left outer join
! 2623: ** (Originally ticket #306. Strengthened by ticket #3300)
! 2624: **
! 2625: ** (4) The subquery is not DISTINCT.
! 2626: **
! 2627: ** (**) At one point restrictions (4) and (5) defined a subset of DISTINCT
! 2628: ** sub-queries that were excluded from this optimization. Restriction
! 2629: ** (4) has since been expanded to exclude all DISTINCT subqueries.
! 2630: **
! 2631: ** (6) The subquery does not use aggregates or the outer query is not
! 2632: ** DISTINCT.
! 2633: **
! 2634: ** (7) The subquery has a FROM clause. TODO: For subqueries without
! 2635: ** A FROM clause, consider adding a FROM close with the special
! 2636: ** table sqlite_once that consists of a single row containing a
! 2637: ** single NULL.
! 2638: **
! 2639: ** (8) The subquery does not use LIMIT or the outer query is not a join.
! 2640: **
! 2641: ** (9) The subquery does not use LIMIT or the outer query does not use
! 2642: ** aggregates.
! 2643: **
! 2644: ** (10) The subquery does not use aggregates or the outer query does not
! 2645: ** use LIMIT.
! 2646: **
! 2647: ** (11) The subquery and the outer query do not both have ORDER BY clauses.
! 2648: **
! 2649: ** (**) Not implemented. Subsumed into restriction (3). Was previously
! 2650: ** a separate restriction deriving from ticket #350.
! 2651: **
! 2652: ** (13) The subquery and outer query do not both use LIMIT.
! 2653: **
! 2654: ** (14) The subquery does not use OFFSET.
! 2655: **
! 2656: ** (15) The outer query is not part of a compound select or the
! 2657: ** subquery does not have a LIMIT clause.
! 2658: ** (See ticket #2339 and ticket [02a8e81d44]).
! 2659: **
! 2660: ** (16) The outer query is not an aggregate or the subquery does
! 2661: ** not contain ORDER BY. (Ticket #2942) This used to not matter
! 2662: ** until we introduced the group_concat() function.
! 2663: **
! 2664: ** (17) The sub-query is not a compound select, or it is a UNION ALL
! 2665: ** compound clause made up entirely of non-aggregate queries, and
! 2666: ** the parent query:
! 2667: **
! 2668: ** * is not itself part of a compound select,
! 2669: ** * is not an aggregate or DISTINCT query, and
! 2670: ** * is not a join
! 2671: **
! 2672: ** The parent and sub-query may contain WHERE clauses. Subject to
! 2673: ** rules (11), (13) and (14), they may also contain ORDER BY,
! 2674: ** LIMIT and OFFSET clauses. The subquery cannot use any compound
! 2675: ** operator other than UNION ALL because all the other compound
! 2676: ** operators have an implied DISTINCT which is disallowed by
! 2677: ** restriction (4).
! 2678: **
! 2679: ** (18) If the sub-query is a compound select, then all terms of the
! 2680: ** ORDER by clause of the parent must be simple references to
! 2681: ** columns of the sub-query.
! 2682: **
! 2683: ** (19) The subquery does not use LIMIT or the outer query does not
! 2684: ** have a WHERE clause.
! 2685: **
! 2686: ** (20) If the sub-query is a compound select, then it must not use
! 2687: ** an ORDER BY clause. Ticket #3773. We could relax this constraint
! 2688: ** somewhat by saying that the terms of the ORDER BY clause must
! 2689: ** appear as unmodified result columns in the outer query. But we
! 2690: ** have other optimizations in mind to deal with that case.
! 2691: **
! 2692: ** (21) The subquery does not use LIMIT or the outer query is not
! 2693: ** DISTINCT. (See ticket [752e1646fc]).
! 2694: **
! 2695: ** In this routine, the "p" parameter is a pointer to the outer query.
! 2696: ** The subquery is p->pSrc->a[iFrom]. isAgg is true if the outer query
! 2697: ** uses aggregates and subqueryIsAgg is true if the subquery uses aggregates.
! 2698: **
! 2699: ** If flattening is not attempted, this routine is a no-op and returns 0.
! 2700: ** If flattening is attempted this routine returns 1.
! 2701: **
! 2702: ** All of the expression analysis must occur on both the outer query and
! 2703: ** the subquery before this routine runs.
! 2704: */
! 2705: static int flattenSubquery(
! 2706: Parse *pParse, /* Parsing context */
! 2707: Select *p, /* The parent or outer SELECT statement */
! 2708: int iFrom, /* Index in p->pSrc->a[] of the inner subquery */
! 2709: int isAgg, /* True if outer SELECT uses aggregate functions */
! 2710: int subqueryIsAgg /* True if the subquery uses aggregate functions */
! 2711: ){
! 2712: const char *zSavedAuthContext = pParse->zAuthContext;
! 2713: Select *pParent;
! 2714: Select *pSub; /* The inner query or "subquery" */
! 2715: Select *pSub1; /* Pointer to the rightmost select in sub-query */
! 2716: SrcList *pSrc; /* The FROM clause of the outer query */
! 2717: SrcList *pSubSrc; /* The FROM clause of the subquery */
! 2718: ExprList *pList; /* The result set of the outer query */
! 2719: int iParent; /* VDBE cursor number of the pSub result set temp table */
! 2720: int i; /* Loop counter */
! 2721: Expr *pWhere; /* The WHERE clause */
! 2722: struct SrcList_item *pSubitem; /* The subquery */
! 2723: sqlite3 *db = pParse->db;
! 2724:
! 2725: /* Check to see if flattening is permitted. Return 0 if not.
! 2726: */
! 2727: assert( p!=0 );
! 2728: assert( p->pPrior==0 ); /* Unable to flatten compound queries */
! 2729: if( db->flags & SQLITE_QueryFlattener ) return 0;
! 2730: pSrc = p->pSrc;
! 2731: assert( pSrc && iFrom>=0 && iFrom<pSrc->nSrc );
! 2732: pSubitem = &pSrc->a[iFrom];
! 2733: iParent = pSubitem->iCursor;
! 2734: pSub = pSubitem->pSelect;
! 2735: assert( pSub!=0 );
! 2736: if( isAgg && subqueryIsAgg ) return 0; /* Restriction (1) */
! 2737: if( subqueryIsAgg && pSrc->nSrc>1 ) return 0; /* Restriction (2) */
! 2738: pSubSrc = pSub->pSrc;
! 2739: assert( pSubSrc );
! 2740: /* Prior to version 3.1.2, when LIMIT and OFFSET had to be simple constants,
! 2741: ** not arbitrary expresssions, we allowed some combining of LIMIT and OFFSET
! 2742: ** because they could be computed at compile-time. But when LIMIT and OFFSET
! 2743: ** became arbitrary expressions, we were forced to add restrictions (13)
! 2744: ** and (14). */
! 2745: if( pSub->pLimit && p->pLimit ) return 0; /* Restriction (13) */
! 2746: if( pSub->pOffset ) return 0; /* Restriction (14) */
! 2747: if( p->pRightmost && pSub->pLimit ){
! 2748: return 0; /* Restriction (15) */
! 2749: }
! 2750: if( pSubSrc->nSrc==0 ) return 0; /* Restriction (7) */
! 2751: if( pSub->selFlags & SF_Distinct ) return 0; /* Restriction (5) */
! 2752: if( pSub->pLimit && (pSrc->nSrc>1 || isAgg) ){
! 2753: return 0; /* Restrictions (8)(9) */
! 2754: }
! 2755: if( (p->selFlags & SF_Distinct)!=0 && subqueryIsAgg ){
! 2756: return 0; /* Restriction (6) */
! 2757: }
! 2758: if( p->pOrderBy && pSub->pOrderBy ){
! 2759: return 0; /* Restriction (11) */
! 2760: }
! 2761: if( isAgg && pSub->pOrderBy ) return 0; /* Restriction (16) */
! 2762: if( pSub->pLimit && p->pWhere ) return 0; /* Restriction (19) */
! 2763: if( pSub->pLimit && (p->selFlags & SF_Distinct)!=0 ){
! 2764: return 0; /* Restriction (21) */
! 2765: }
! 2766:
! 2767: /* OBSOLETE COMMENT 1:
! 2768: ** Restriction 3: If the subquery is a join, make sure the subquery is
! 2769: ** not used as the right operand of an outer join. Examples of why this
! 2770: ** is not allowed:
! 2771: **
! 2772: ** t1 LEFT OUTER JOIN (t2 JOIN t3)
! 2773: **
! 2774: ** If we flatten the above, we would get
! 2775: **
! 2776: ** (t1 LEFT OUTER JOIN t2) JOIN t3
! 2777: **
! 2778: ** which is not at all the same thing.
! 2779: **
! 2780: ** OBSOLETE COMMENT 2:
! 2781: ** Restriction 12: If the subquery is the right operand of a left outer
! 2782: ** join, make sure the subquery has no WHERE clause.
! 2783: ** An examples of why this is not allowed:
! 2784: **
! 2785: ** t1 LEFT OUTER JOIN (SELECT * FROM t2 WHERE t2.x>0)
! 2786: **
! 2787: ** If we flatten the above, we would get
! 2788: **
! 2789: ** (t1 LEFT OUTER JOIN t2) WHERE t2.x>0
! 2790: **
! 2791: ** But the t2.x>0 test will always fail on a NULL row of t2, which
! 2792: ** effectively converts the OUTER JOIN into an INNER JOIN.
! 2793: **
! 2794: ** THIS OVERRIDES OBSOLETE COMMENTS 1 AND 2 ABOVE:
! 2795: ** Ticket #3300 shows that flattening the right term of a LEFT JOIN
! 2796: ** is fraught with danger. Best to avoid the whole thing. If the
! 2797: ** subquery is the right term of a LEFT JOIN, then do not flatten.
! 2798: */
! 2799: if( (pSubitem->jointype & JT_OUTER)!=0 ){
! 2800: return 0;
! 2801: }
! 2802:
! 2803: /* Restriction 17: If the sub-query is a compound SELECT, then it must
! 2804: ** use only the UNION ALL operator. And none of the simple select queries
! 2805: ** that make up the compound SELECT are allowed to be aggregate or distinct
! 2806: ** queries.
! 2807: */
! 2808: if( pSub->pPrior ){
! 2809: if( pSub->pOrderBy ){
! 2810: return 0; /* Restriction 20 */
! 2811: }
! 2812: if( isAgg || (p->selFlags & SF_Distinct)!=0 || pSrc->nSrc!=1 ){
! 2813: return 0;
! 2814: }
! 2815: for(pSub1=pSub; pSub1; pSub1=pSub1->pPrior){
! 2816: testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct );
! 2817: testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Aggregate );
! 2818: assert( pSub->pSrc!=0 );
! 2819: if( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))!=0
! 2820: || (pSub1->pPrior && pSub1->op!=TK_ALL)
! 2821: || pSub1->pSrc->nSrc<1
! 2822: ){
! 2823: return 0;
! 2824: }
! 2825: testcase( pSub1->pSrc->nSrc>1 );
! 2826: }
! 2827:
! 2828: /* Restriction 18. */
! 2829: if( p->pOrderBy ){
! 2830: int ii;
! 2831: for(ii=0; ii<p->pOrderBy->nExpr; ii++){
! 2832: if( p->pOrderBy->a[ii].iOrderByCol==0 ) return 0;
! 2833: }
! 2834: }
! 2835: }
! 2836:
! 2837: /***** If we reach this point, flattening is permitted. *****/
! 2838:
! 2839: /* Authorize the subquery */
! 2840: pParse->zAuthContext = pSubitem->zName;
! 2841: sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0);
! 2842: pParse->zAuthContext = zSavedAuthContext;
! 2843:
! 2844: /* If the sub-query is a compound SELECT statement, then (by restrictions
! 2845: ** 17 and 18 above) it must be a UNION ALL and the parent query must
! 2846: ** be of the form:
! 2847: **
! 2848: ** SELECT <expr-list> FROM (<sub-query>) <where-clause>
! 2849: **
! 2850: ** followed by any ORDER BY, LIMIT and/or OFFSET clauses. This block
! 2851: ** creates N-1 copies of the parent query without any ORDER BY, LIMIT or
! 2852: ** OFFSET clauses and joins them to the left-hand-side of the original
! 2853: ** using UNION ALL operators. In this case N is the number of simple
! 2854: ** select statements in the compound sub-query.
! 2855: **
! 2856: ** Example:
! 2857: **
! 2858: ** SELECT a+1 FROM (
! 2859: ** SELECT x FROM tab
! 2860: ** UNION ALL
! 2861: ** SELECT y FROM tab
! 2862: ** UNION ALL
! 2863: ** SELECT abs(z*2) FROM tab2
! 2864: ** ) WHERE a!=5 ORDER BY 1
! 2865: **
! 2866: ** Transformed into:
! 2867: **
! 2868: ** SELECT x+1 FROM tab WHERE x+1!=5
! 2869: ** UNION ALL
! 2870: ** SELECT y+1 FROM tab WHERE y+1!=5
! 2871: ** UNION ALL
! 2872: ** SELECT abs(z*2)+1 FROM tab2 WHERE abs(z*2)+1!=5
! 2873: ** ORDER BY 1
! 2874: **
! 2875: ** We call this the "compound-subquery flattening".
! 2876: */
! 2877: for(pSub=pSub->pPrior; pSub; pSub=pSub->pPrior){
! 2878: Select *pNew;
! 2879: ExprList *pOrderBy = p->pOrderBy;
! 2880: Expr *pLimit = p->pLimit;
! 2881: Select *pPrior = p->pPrior;
! 2882: p->pOrderBy = 0;
! 2883: p->pSrc = 0;
! 2884: p->pPrior = 0;
! 2885: p->pLimit = 0;
! 2886: pNew = sqlite3SelectDup(db, p, 0);
! 2887: p->pLimit = pLimit;
! 2888: p->pOrderBy = pOrderBy;
! 2889: p->pSrc = pSrc;
! 2890: p->op = TK_ALL;
! 2891: p->pRightmost = 0;
! 2892: if( pNew==0 ){
! 2893: pNew = pPrior;
! 2894: }else{
! 2895: pNew->pPrior = pPrior;
! 2896: pNew->pRightmost = 0;
! 2897: }
! 2898: p->pPrior = pNew;
! 2899: if( db->mallocFailed ) return 1;
! 2900: }
! 2901:
! 2902: /* Begin flattening the iFrom-th entry of the FROM clause
! 2903: ** in the outer query.
! 2904: */
! 2905: pSub = pSub1 = pSubitem->pSelect;
! 2906:
! 2907: /* Delete the transient table structure associated with the
! 2908: ** subquery
! 2909: */
! 2910: sqlite3DbFree(db, pSubitem->zDatabase);
! 2911: sqlite3DbFree(db, pSubitem->zName);
! 2912: sqlite3DbFree(db, pSubitem->zAlias);
! 2913: pSubitem->zDatabase = 0;
! 2914: pSubitem->zName = 0;
! 2915: pSubitem->zAlias = 0;
! 2916: pSubitem->pSelect = 0;
! 2917:
! 2918: /* Defer deleting the Table object associated with the
! 2919: ** subquery until code generation is
! 2920: ** complete, since there may still exist Expr.pTab entries that
! 2921: ** refer to the subquery even after flattening. Ticket #3346.
! 2922: **
! 2923: ** pSubitem->pTab is always non-NULL by test restrictions and tests above.
! 2924: */
! 2925: if( ALWAYS(pSubitem->pTab!=0) ){
! 2926: Table *pTabToDel = pSubitem->pTab;
! 2927: if( pTabToDel->nRef==1 ){
! 2928: Parse *pToplevel = sqlite3ParseToplevel(pParse);
! 2929: pTabToDel->pNextZombie = pToplevel->pZombieTab;
! 2930: pToplevel->pZombieTab = pTabToDel;
! 2931: }else{
! 2932: pTabToDel->nRef--;
! 2933: }
! 2934: pSubitem->pTab = 0;
! 2935: }
! 2936:
! 2937: /* The following loop runs once for each term in a compound-subquery
! 2938: ** flattening (as described above). If we are doing a different kind
! 2939: ** of flattening - a flattening other than a compound-subquery flattening -
! 2940: ** then this loop only runs once.
! 2941: **
! 2942: ** This loop moves all of the FROM elements of the subquery into the
! 2943: ** the FROM clause of the outer query. Before doing this, remember
! 2944: ** the cursor number for the original outer query FROM element in
! 2945: ** iParent. The iParent cursor will never be used. Subsequent code
! 2946: ** will scan expressions looking for iParent references and replace
! 2947: ** those references with expressions that resolve to the subquery FROM
! 2948: ** elements we are now copying in.
! 2949: */
! 2950: for(pParent=p; pParent; pParent=pParent->pPrior, pSub=pSub->pPrior){
! 2951: int nSubSrc;
! 2952: u8 jointype = 0;
! 2953: pSubSrc = pSub->pSrc; /* FROM clause of subquery */
! 2954: nSubSrc = pSubSrc->nSrc; /* Number of terms in subquery FROM clause */
! 2955: pSrc = pParent->pSrc; /* FROM clause of the outer query */
! 2956:
! 2957: if( pSrc ){
! 2958: assert( pParent==p ); /* First time through the loop */
! 2959: jointype = pSubitem->jointype;
! 2960: }else{
! 2961: assert( pParent!=p ); /* 2nd and subsequent times through the loop */
! 2962: pSrc = pParent->pSrc = sqlite3SrcListAppend(db, 0, 0, 0);
! 2963: if( pSrc==0 ){
! 2964: assert( db->mallocFailed );
! 2965: break;
! 2966: }
! 2967: }
! 2968:
! 2969: /* The subquery uses a single slot of the FROM clause of the outer
! 2970: ** query. If the subquery has more than one element in its FROM clause,
! 2971: ** then expand the outer query to make space for it to hold all elements
! 2972: ** of the subquery.
! 2973: **
! 2974: ** Example:
! 2975: **
! 2976: ** SELECT * FROM tabA, (SELECT * FROM sub1, sub2), tabB;
! 2977: **
! 2978: ** The outer query has 3 slots in its FROM clause. One slot of the
! 2979: ** outer query (the middle slot) is used by the subquery. The next
! 2980: ** block of code will expand the out query to 4 slots. The middle
! 2981: ** slot is expanded to two slots in order to make space for the
! 2982: ** two elements in the FROM clause of the subquery.
! 2983: */
! 2984: if( nSubSrc>1 ){
! 2985: pParent->pSrc = pSrc = sqlite3SrcListEnlarge(db, pSrc, nSubSrc-1,iFrom+1);
! 2986: if( db->mallocFailed ){
! 2987: break;
! 2988: }
! 2989: }
! 2990:
! 2991: /* Transfer the FROM clause terms from the subquery into the
! 2992: ** outer query.
! 2993: */
! 2994: for(i=0; i<nSubSrc; i++){
! 2995: sqlite3IdListDelete(db, pSrc->a[i+iFrom].pUsing);
! 2996: pSrc->a[i+iFrom] = pSubSrc->a[i];
! 2997: memset(&pSubSrc->a[i], 0, sizeof(pSubSrc->a[i]));
! 2998: }
! 2999: pSrc->a[iFrom].jointype = jointype;
! 3000:
! 3001: /* Now begin substituting subquery result set expressions for
! 3002: ** references to the iParent in the outer query.
! 3003: **
! 3004: ** Example:
! 3005: **
! 3006: ** SELECT a+5, b*10 FROM (SELECT x*3 AS a, y+10 AS b FROM t1) WHERE a>b;
! 3007: ** \ \_____________ subquery __________/ /
! 3008: ** \_____________________ outer query ______________________________/
! 3009: **
! 3010: ** We look at every expression in the outer query and every place we see
! 3011: ** "a" we substitute "x*3" and every place we see "b" we substitute "y+10".
! 3012: */
! 3013: pList = pParent->pEList;
! 3014: for(i=0; i<pList->nExpr; i++){
! 3015: if( pList->a[i].zName==0 ){
! 3016: const char *zSpan = pList->a[i].zSpan;
! 3017: if( ALWAYS(zSpan) ){
! 3018: pList->a[i].zName = sqlite3DbStrDup(db, zSpan);
! 3019: }
! 3020: }
! 3021: }
! 3022: substExprList(db, pParent->pEList, iParent, pSub->pEList);
! 3023: if( isAgg ){
! 3024: substExprList(db, pParent->pGroupBy, iParent, pSub->pEList);
! 3025: pParent->pHaving = substExpr(db, pParent->pHaving, iParent, pSub->pEList);
! 3026: }
! 3027: if( pSub->pOrderBy ){
! 3028: assert( pParent->pOrderBy==0 );
! 3029: pParent->pOrderBy = pSub->pOrderBy;
! 3030: pSub->pOrderBy = 0;
! 3031: }else if( pParent->pOrderBy ){
! 3032: substExprList(db, pParent->pOrderBy, iParent, pSub->pEList);
! 3033: }
! 3034: if( pSub->pWhere ){
! 3035: pWhere = sqlite3ExprDup(db, pSub->pWhere, 0);
! 3036: }else{
! 3037: pWhere = 0;
! 3038: }
! 3039: if( subqueryIsAgg ){
! 3040: assert( pParent->pHaving==0 );
! 3041: pParent->pHaving = pParent->pWhere;
! 3042: pParent->pWhere = pWhere;
! 3043: pParent->pHaving = substExpr(db, pParent->pHaving, iParent, pSub->pEList);
! 3044: pParent->pHaving = sqlite3ExprAnd(db, pParent->pHaving,
! 3045: sqlite3ExprDup(db, pSub->pHaving, 0));
! 3046: assert( pParent->pGroupBy==0 );
! 3047: pParent->pGroupBy = sqlite3ExprListDup(db, pSub->pGroupBy, 0);
! 3048: }else{
! 3049: pParent->pWhere = substExpr(db, pParent->pWhere, iParent, pSub->pEList);
! 3050: pParent->pWhere = sqlite3ExprAnd(db, pParent->pWhere, pWhere);
! 3051: }
! 3052:
! 3053: /* The flattened query is distinct if either the inner or the
! 3054: ** outer query is distinct.
! 3055: */
! 3056: pParent->selFlags |= pSub->selFlags & SF_Distinct;
! 3057:
! 3058: /*
! 3059: ** SELECT ... FROM (SELECT ... LIMIT a OFFSET b) LIMIT x OFFSET y;
! 3060: **
! 3061: ** One is tempted to try to add a and b to combine the limits. But this
! 3062: ** does not work if either limit is negative.
! 3063: */
! 3064: if( pSub->pLimit ){
! 3065: pParent->pLimit = pSub->pLimit;
! 3066: pSub->pLimit = 0;
! 3067: }
! 3068: }
! 3069:
! 3070: /* Finially, delete what is left of the subquery and return
! 3071: ** success.
! 3072: */
! 3073: sqlite3SelectDelete(db, pSub1);
! 3074:
! 3075: return 1;
! 3076: }
! 3077: #endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */
! 3078:
! 3079: /*
! 3080: ** Analyze the SELECT statement passed as an argument to see if it
! 3081: ** is a min() or max() query. Return WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX if
! 3082: ** it is, or 0 otherwise. At present, a query is considered to be
! 3083: ** a min()/max() query if:
! 3084: **
! 3085: ** 1. There is a single object in the FROM clause.
! 3086: **
! 3087: ** 2. There is a single expression in the result set, and it is
! 3088: ** either min(x) or max(x), where x is a column reference.
! 3089: */
! 3090: static u8 minMaxQuery(Select *p){
! 3091: Expr *pExpr;
! 3092: ExprList *pEList = p->pEList;
! 3093:
! 3094: if( pEList->nExpr!=1 ) return WHERE_ORDERBY_NORMAL;
! 3095: pExpr = pEList->a[0].pExpr;
! 3096: if( pExpr->op!=TK_AGG_FUNCTION ) return 0;
! 3097: if( NEVER(ExprHasProperty(pExpr, EP_xIsSelect)) ) return 0;
! 3098: pEList = pExpr->x.pList;
! 3099: if( pEList==0 || pEList->nExpr!=1 ) return 0;
! 3100: if( pEList->a[0].pExpr->op!=TK_AGG_COLUMN ) return WHERE_ORDERBY_NORMAL;
! 3101: assert( !ExprHasProperty(pExpr, EP_IntValue) );
! 3102: if( sqlite3StrICmp(pExpr->u.zToken,"min")==0 ){
! 3103: return WHERE_ORDERBY_MIN;
! 3104: }else if( sqlite3StrICmp(pExpr->u.zToken,"max")==0 ){
! 3105: return WHERE_ORDERBY_MAX;
! 3106: }
! 3107: return WHERE_ORDERBY_NORMAL;
! 3108: }
! 3109:
! 3110: /*
! 3111: ** The select statement passed as the first argument is an aggregate query.
! 3112: ** The second argment is the associated aggregate-info object. This
! 3113: ** function tests if the SELECT is of the form:
! 3114: **
! 3115: ** SELECT count(*) FROM <tbl>
! 3116: **
! 3117: ** where table is a database table, not a sub-select or view. If the query
! 3118: ** does match this pattern, then a pointer to the Table object representing
! 3119: ** <tbl> is returned. Otherwise, 0 is returned.
! 3120: */
! 3121: static Table *isSimpleCount(Select *p, AggInfo *pAggInfo){
! 3122: Table *pTab;
! 3123: Expr *pExpr;
! 3124:
! 3125: assert( !p->pGroupBy );
! 3126:
! 3127: if( p->pWhere || p->pEList->nExpr!=1
! 3128: || p->pSrc->nSrc!=1 || p->pSrc->a[0].pSelect
! 3129: ){
! 3130: return 0;
! 3131: }
! 3132: pTab = p->pSrc->a[0].pTab;
! 3133: pExpr = p->pEList->a[0].pExpr;
! 3134: assert( pTab && !pTab->pSelect && pExpr );
! 3135:
! 3136: if( IsVirtual(pTab) ) return 0;
! 3137: if( pExpr->op!=TK_AGG_FUNCTION ) return 0;
! 3138: if( (pAggInfo->aFunc[0].pFunc->flags&SQLITE_FUNC_COUNT)==0 ) return 0;
! 3139: if( pExpr->flags&EP_Distinct ) return 0;
! 3140:
! 3141: return pTab;
! 3142: }
! 3143:
! 3144: /*
! 3145: ** If the source-list item passed as an argument was augmented with an
! 3146: ** INDEXED BY clause, then try to locate the specified index. If there
! 3147: ** was such a clause and the named index cannot be found, return
! 3148: ** SQLITE_ERROR and leave an error in pParse. Otherwise, populate
! 3149: ** pFrom->pIndex and return SQLITE_OK.
! 3150: */
! 3151: int sqlite3IndexedByLookup(Parse *pParse, struct SrcList_item *pFrom){
! 3152: if( pFrom->pTab && pFrom->zIndex ){
! 3153: Table *pTab = pFrom->pTab;
! 3154: char *zIndex = pFrom->zIndex;
! 3155: Index *pIdx;
! 3156: for(pIdx=pTab->pIndex;
! 3157: pIdx && sqlite3StrICmp(pIdx->zName, zIndex);
! 3158: pIdx=pIdx->pNext
! 3159: );
! 3160: if( !pIdx ){
! 3161: sqlite3ErrorMsg(pParse, "no such index: %s", zIndex, 0);
! 3162: pParse->checkSchema = 1;
! 3163: return SQLITE_ERROR;
! 3164: }
! 3165: pFrom->pIndex = pIdx;
! 3166: }
! 3167: return SQLITE_OK;
! 3168: }
! 3169:
! 3170: /*
! 3171: ** This routine is a Walker callback for "expanding" a SELECT statement.
! 3172: ** "Expanding" means to do the following:
! 3173: **
! 3174: ** (1) Make sure VDBE cursor numbers have been assigned to every
! 3175: ** element of the FROM clause.
! 3176: **
! 3177: ** (2) Fill in the pTabList->a[].pTab fields in the SrcList that
! 3178: ** defines FROM clause. When views appear in the FROM clause,
! 3179: ** fill pTabList->a[].pSelect with a copy of the SELECT statement
! 3180: ** that implements the view. A copy is made of the view's SELECT
! 3181: ** statement so that we can freely modify or delete that statement
! 3182: ** without worrying about messing up the presistent representation
! 3183: ** of the view.
! 3184: **
! 3185: ** (3) Add terms to the WHERE clause to accomodate the NATURAL keyword
! 3186: ** on joins and the ON and USING clause of joins.
! 3187: **
! 3188: ** (4) Scan the list of columns in the result set (pEList) looking
! 3189: ** for instances of the "*" operator or the TABLE.* operator.
! 3190: ** If found, expand each "*" to be every column in every table
! 3191: ** and TABLE.* to be every column in TABLE.
! 3192: **
! 3193: */
! 3194: static int selectExpander(Walker *pWalker, Select *p){
! 3195: Parse *pParse = pWalker->pParse;
! 3196: int i, j, k;
! 3197: SrcList *pTabList;
! 3198: ExprList *pEList;
! 3199: struct SrcList_item *pFrom;
! 3200: sqlite3 *db = pParse->db;
! 3201:
! 3202: if( db->mallocFailed ){
! 3203: return WRC_Abort;
! 3204: }
! 3205: if( NEVER(p->pSrc==0) || (p->selFlags & SF_Expanded)!=0 ){
! 3206: return WRC_Prune;
! 3207: }
! 3208: p->selFlags |= SF_Expanded;
! 3209: pTabList = p->pSrc;
! 3210: pEList = p->pEList;
! 3211:
! 3212: /* Make sure cursor numbers have been assigned to all entries in
! 3213: ** the FROM clause of the SELECT statement.
! 3214: */
! 3215: sqlite3SrcListAssignCursors(pParse, pTabList);
! 3216:
! 3217: /* Look up every table named in the FROM clause of the select. If
! 3218: ** an entry of the FROM clause is a subquery instead of a table or view,
! 3219: ** then create a transient table structure to describe the subquery.
! 3220: */
! 3221: for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
! 3222: Table *pTab;
! 3223: if( pFrom->pTab!=0 ){
! 3224: /* This statement has already been prepared. There is no need
! 3225: ** to go further. */
! 3226: assert( i==0 );
! 3227: return WRC_Prune;
! 3228: }
! 3229: if( pFrom->zName==0 ){
! 3230: #ifndef SQLITE_OMIT_SUBQUERY
! 3231: Select *pSel = pFrom->pSelect;
! 3232: /* A sub-query in the FROM clause of a SELECT */
! 3233: assert( pSel!=0 );
! 3234: assert( pFrom->pTab==0 );
! 3235: sqlite3WalkSelect(pWalker, pSel);
! 3236: pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table));
! 3237: if( pTab==0 ) return WRC_Abort;
! 3238: pTab->nRef = 1;
! 3239: pTab->zName = sqlite3MPrintf(db, "sqlite_subquery_%p_", (void*)pTab);
! 3240: while( pSel->pPrior ){ pSel = pSel->pPrior; }
! 3241: selectColumnsFromExprList(pParse, pSel->pEList, &pTab->nCol, &pTab->aCol);
! 3242: pTab->iPKey = -1;
! 3243: pTab->nRowEst = 1000000;
! 3244: pTab->tabFlags |= TF_Ephemeral;
! 3245: #endif
! 3246: }else{
! 3247: /* An ordinary table or view name in the FROM clause */
! 3248: assert( pFrom->pTab==0 );
! 3249: pFrom->pTab = pTab =
! 3250: sqlite3LocateTable(pParse,0,pFrom->zName,pFrom->zDatabase);
! 3251: if( pTab==0 ) return WRC_Abort;
! 3252: pTab->nRef++;
! 3253: #if !defined(SQLITE_OMIT_VIEW) || !defined (SQLITE_OMIT_VIRTUALTABLE)
! 3254: if( pTab->pSelect || IsVirtual(pTab) ){
! 3255: /* We reach here if the named table is a really a view */
! 3256: if( sqlite3ViewGetColumnNames(pParse, pTab) ) return WRC_Abort;
! 3257: assert( pFrom->pSelect==0 );
! 3258: pFrom->pSelect = sqlite3SelectDup(db, pTab->pSelect, 0);
! 3259: sqlite3WalkSelect(pWalker, pFrom->pSelect);
! 3260: }
! 3261: #endif
! 3262: }
! 3263:
! 3264: /* Locate the index named by the INDEXED BY clause, if any. */
! 3265: if( sqlite3IndexedByLookup(pParse, pFrom) ){
! 3266: return WRC_Abort;
! 3267: }
! 3268: }
! 3269:
! 3270: /* Process NATURAL keywords, and ON and USING clauses of joins.
! 3271: */
! 3272: if( db->mallocFailed || sqliteProcessJoin(pParse, p) ){
! 3273: return WRC_Abort;
! 3274: }
! 3275:
! 3276: /* For every "*" that occurs in the column list, insert the names of
! 3277: ** all columns in all tables. And for every TABLE.* insert the names
! 3278: ** of all columns in TABLE. The parser inserted a special expression
! 3279: ** with the TK_ALL operator for each "*" that it found in the column list.
! 3280: ** The following code just has to locate the TK_ALL expressions and expand
! 3281: ** each one to the list of all columns in all tables.
! 3282: **
! 3283: ** The first loop just checks to see if there are any "*" operators
! 3284: ** that need expanding.
! 3285: */
! 3286: for(k=0; k<pEList->nExpr; k++){
! 3287: Expr *pE = pEList->a[k].pExpr;
! 3288: if( pE->op==TK_ALL ) break;
! 3289: assert( pE->op!=TK_DOT || pE->pRight!=0 );
! 3290: assert( pE->op!=TK_DOT || (pE->pLeft!=0 && pE->pLeft->op==TK_ID) );
! 3291: if( pE->op==TK_DOT && pE->pRight->op==TK_ALL ) break;
! 3292: }
! 3293: if( k<pEList->nExpr ){
! 3294: /*
! 3295: ** If we get here it means the result set contains one or more "*"
! 3296: ** operators that need to be expanded. Loop through each expression
! 3297: ** in the result set and expand them one by one.
! 3298: */
! 3299: struct ExprList_item *a = pEList->a;
! 3300: ExprList *pNew = 0;
! 3301: int flags = pParse->db->flags;
! 3302: int longNames = (flags & SQLITE_FullColNames)!=0
! 3303: && (flags & SQLITE_ShortColNames)==0;
! 3304:
! 3305: for(k=0; k<pEList->nExpr; k++){
! 3306: Expr *pE = a[k].pExpr;
! 3307: assert( pE->op!=TK_DOT || pE->pRight!=0 );
! 3308: if( pE->op!=TK_ALL && (pE->op!=TK_DOT || pE->pRight->op!=TK_ALL) ){
! 3309: /* This particular expression does not need to be expanded.
! 3310: */
! 3311: pNew = sqlite3ExprListAppend(pParse, pNew, a[k].pExpr);
! 3312: if( pNew ){
! 3313: pNew->a[pNew->nExpr-1].zName = a[k].zName;
! 3314: pNew->a[pNew->nExpr-1].zSpan = a[k].zSpan;
! 3315: a[k].zName = 0;
! 3316: a[k].zSpan = 0;
! 3317: }
! 3318: a[k].pExpr = 0;
! 3319: }else{
! 3320: /* This expression is a "*" or a "TABLE.*" and needs to be
! 3321: ** expanded. */
! 3322: int tableSeen = 0; /* Set to 1 when TABLE matches */
! 3323: char *zTName; /* text of name of TABLE */
! 3324: if( pE->op==TK_DOT ){
! 3325: assert( pE->pLeft!=0 );
! 3326: assert( !ExprHasProperty(pE->pLeft, EP_IntValue) );
! 3327: zTName = pE->pLeft->u.zToken;
! 3328: }else{
! 3329: zTName = 0;
! 3330: }
! 3331: for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
! 3332: Table *pTab = pFrom->pTab;
! 3333: char *zTabName = pFrom->zAlias;
! 3334: if( zTabName==0 ){
! 3335: zTabName = pTab->zName;
! 3336: }
! 3337: if( db->mallocFailed ) break;
! 3338: if( zTName && sqlite3StrICmp(zTName, zTabName)!=0 ){
! 3339: continue;
! 3340: }
! 3341: tableSeen = 1;
! 3342: for(j=0; j<pTab->nCol; j++){
! 3343: Expr *pExpr, *pRight;
! 3344: char *zName = pTab->aCol[j].zName;
! 3345: char *zColname; /* The computed column name */
! 3346: char *zToFree; /* Malloced string that needs to be freed */
! 3347: Token sColname; /* Computed column name as a token */
! 3348:
! 3349: /* If a column is marked as 'hidden' (currently only possible
! 3350: ** for virtual tables), do not include it in the expanded
! 3351: ** result-set list.
! 3352: */
! 3353: if( IsHiddenColumn(&pTab->aCol[j]) ){
! 3354: assert(IsVirtual(pTab));
! 3355: continue;
! 3356: }
! 3357:
! 3358: if( i>0 && zTName==0 ){
! 3359: if( (pFrom->jointype & JT_NATURAL)!=0
! 3360: && tableAndColumnIndex(pTabList, i, zName, 0, 0)
! 3361: ){
! 3362: /* In a NATURAL join, omit the join columns from the
! 3363: ** table to the right of the join */
! 3364: continue;
! 3365: }
! 3366: if( sqlite3IdListIndex(pFrom->pUsing, zName)>=0 ){
! 3367: /* In a join with a USING clause, omit columns in the
! 3368: ** using clause from the table on the right. */
! 3369: continue;
! 3370: }
! 3371: }
! 3372: pRight = sqlite3Expr(db, TK_ID, zName);
! 3373: zColname = zName;
! 3374: zToFree = 0;
! 3375: if( longNames || pTabList->nSrc>1 ){
! 3376: Expr *pLeft;
! 3377: pLeft = sqlite3Expr(db, TK_ID, zTabName);
! 3378: pExpr = sqlite3PExpr(pParse, TK_DOT, pLeft, pRight, 0);
! 3379: if( longNames ){
! 3380: zColname = sqlite3MPrintf(db, "%s.%s", zTabName, zName);
! 3381: zToFree = zColname;
! 3382: }
! 3383: }else{
! 3384: pExpr = pRight;
! 3385: }
! 3386: pNew = sqlite3ExprListAppend(pParse, pNew, pExpr);
! 3387: sColname.z = zColname;
! 3388: sColname.n = sqlite3Strlen30(zColname);
! 3389: sqlite3ExprListSetName(pParse, pNew, &sColname, 0);
! 3390: sqlite3DbFree(db, zToFree);
! 3391: }
! 3392: }
! 3393: if( !tableSeen ){
! 3394: if( zTName ){
! 3395: sqlite3ErrorMsg(pParse, "no such table: %s", zTName);
! 3396: }else{
! 3397: sqlite3ErrorMsg(pParse, "no tables specified");
! 3398: }
! 3399: }
! 3400: }
! 3401: }
! 3402: sqlite3ExprListDelete(db, pEList);
! 3403: p->pEList = pNew;
! 3404: }
! 3405: #if SQLITE_MAX_COLUMN
! 3406: if( p->pEList && p->pEList->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){
! 3407: sqlite3ErrorMsg(pParse, "too many columns in result set");
! 3408: }
! 3409: #endif
! 3410: return WRC_Continue;
! 3411: }
! 3412:
! 3413: /*
! 3414: ** No-op routine for the parse-tree walker.
! 3415: **
! 3416: ** When this routine is the Walker.xExprCallback then expression trees
! 3417: ** are walked without any actions being taken at each node. Presumably,
! 3418: ** when this routine is used for Walker.xExprCallback then
! 3419: ** Walker.xSelectCallback is set to do something useful for every
! 3420: ** subquery in the parser tree.
! 3421: */
! 3422: static int exprWalkNoop(Walker *NotUsed, Expr *NotUsed2){
! 3423: UNUSED_PARAMETER2(NotUsed, NotUsed2);
! 3424: return WRC_Continue;
! 3425: }
! 3426:
! 3427: /*
! 3428: ** This routine "expands" a SELECT statement and all of its subqueries.
! 3429: ** For additional information on what it means to "expand" a SELECT
! 3430: ** statement, see the comment on the selectExpand worker callback above.
! 3431: **
! 3432: ** Expanding a SELECT statement is the first step in processing a
! 3433: ** SELECT statement. The SELECT statement must be expanded before
! 3434: ** name resolution is performed.
! 3435: **
! 3436: ** If anything goes wrong, an error message is written into pParse.
! 3437: ** The calling function can detect the problem by looking at pParse->nErr
! 3438: ** and/or pParse->db->mallocFailed.
! 3439: */
! 3440: static void sqlite3SelectExpand(Parse *pParse, Select *pSelect){
! 3441: Walker w;
! 3442: w.xSelectCallback = selectExpander;
! 3443: w.xExprCallback = exprWalkNoop;
! 3444: w.pParse = pParse;
! 3445: sqlite3WalkSelect(&w, pSelect);
! 3446: }
! 3447:
! 3448:
! 3449: #ifndef SQLITE_OMIT_SUBQUERY
! 3450: /*
! 3451: ** This is a Walker.xSelectCallback callback for the sqlite3SelectTypeInfo()
! 3452: ** interface.
! 3453: **
! 3454: ** For each FROM-clause subquery, add Column.zType and Column.zColl
! 3455: ** information to the Table structure that represents the result set
! 3456: ** of that subquery.
! 3457: **
! 3458: ** The Table structure that represents the result set was constructed
! 3459: ** by selectExpander() but the type and collation information was omitted
! 3460: ** at that point because identifiers had not yet been resolved. This
! 3461: ** routine is called after identifier resolution.
! 3462: */
! 3463: static int selectAddSubqueryTypeInfo(Walker *pWalker, Select *p){
! 3464: Parse *pParse;
! 3465: int i;
! 3466: SrcList *pTabList;
! 3467: struct SrcList_item *pFrom;
! 3468:
! 3469: assert( p->selFlags & SF_Resolved );
! 3470: if( (p->selFlags & SF_HasTypeInfo)==0 ){
! 3471: p->selFlags |= SF_HasTypeInfo;
! 3472: pParse = pWalker->pParse;
! 3473: pTabList = p->pSrc;
! 3474: for(i=0, pFrom=pTabList->a; i<pTabList->nSrc; i++, pFrom++){
! 3475: Table *pTab = pFrom->pTab;
! 3476: if( ALWAYS(pTab!=0) && (pTab->tabFlags & TF_Ephemeral)!=0 ){
! 3477: /* A sub-query in the FROM clause of a SELECT */
! 3478: Select *pSel = pFrom->pSelect;
! 3479: assert( pSel );
! 3480: while( pSel->pPrior ) pSel = pSel->pPrior;
! 3481: selectAddColumnTypeAndCollation(pParse, pTab->nCol, pTab->aCol, pSel);
! 3482: }
! 3483: }
! 3484: }
! 3485: return WRC_Continue;
! 3486: }
! 3487: #endif
! 3488:
! 3489:
! 3490: /*
! 3491: ** This routine adds datatype and collating sequence information to
! 3492: ** the Table structures of all FROM-clause subqueries in a
! 3493: ** SELECT statement.
! 3494: **
! 3495: ** Use this routine after name resolution.
! 3496: */
! 3497: static void sqlite3SelectAddTypeInfo(Parse *pParse, Select *pSelect){
! 3498: #ifndef SQLITE_OMIT_SUBQUERY
! 3499: Walker w;
! 3500: w.xSelectCallback = selectAddSubqueryTypeInfo;
! 3501: w.xExprCallback = exprWalkNoop;
! 3502: w.pParse = pParse;
! 3503: sqlite3WalkSelect(&w, pSelect);
! 3504: #endif
! 3505: }
! 3506:
! 3507:
! 3508: /*
! 3509: ** This routine sets of a SELECT statement for processing. The
! 3510: ** following is accomplished:
! 3511: **
! 3512: ** * VDBE Cursor numbers are assigned to all FROM-clause terms.
! 3513: ** * Ephemeral Table objects are created for all FROM-clause subqueries.
! 3514: ** * ON and USING clauses are shifted into WHERE statements
! 3515: ** * Wildcards "*" and "TABLE.*" in result sets are expanded.
! 3516: ** * Identifiers in expression are matched to tables.
! 3517: **
! 3518: ** This routine acts recursively on all subqueries within the SELECT.
! 3519: */
! 3520: void sqlite3SelectPrep(
! 3521: Parse *pParse, /* The parser context */
! 3522: Select *p, /* The SELECT statement being coded. */
! 3523: NameContext *pOuterNC /* Name context for container */
! 3524: ){
! 3525: sqlite3 *db;
! 3526: if( NEVER(p==0) ) return;
! 3527: db = pParse->db;
! 3528: if( p->selFlags & SF_HasTypeInfo ) return;
! 3529: sqlite3SelectExpand(pParse, p);
! 3530: if( pParse->nErr || db->mallocFailed ) return;
! 3531: sqlite3ResolveSelectNames(pParse, p, pOuterNC);
! 3532: if( pParse->nErr || db->mallocFailed ) return;
! 3533: sqlite3SelectAddTypeInfo(pParse, p);
! 3534: }
! 3535:
! 3536: /*
! 3537: ** Reset the aggregate accumulator.
! 3538: **
! 3539: ** The aggregate accumulator is a set of memory cells that hold
! 3540: ** intermediate results while calculating an aggregate. This
! 3541: ** routine simply stores NULLs in all of those memory cells.
! 3542: */
! 3543: static void resetAccumulator(Parse *pParse, AggInfo *pAggInfo){
! 3544: Vdbe *v = pParse->pVdbe;
! 3545: int i;
! 3546: struct AggInfo_func *pFunc;
! 3547: if( pAggInfo->nFunc+pAggInfo->nColumn==0 ){
! 3548: return;
! 3549: }
! 3550: for(i=0; i<pAggInfo->nColumn; i++){
! 3551: sqlite3VdbeAddOp2(v, OP_Null, 0, pAggInfo->aCol[i].iMem);
! 3552: }
! 3553: for(pFunc=pAggInfo->aFunc, i=0; i<pAggInfo->nFunc; i++, pFunc++){
! 3554: sqlite3VdbeAddOp2(v, OP_Null, 0, pFunc->iMem);
! 3555: if( pFunc->iDistinct>=0 ){
! 3556: Expr *pE = pFunc->pExpr;
! 3557: assert( !ExprHasProperty(pE, EP_xIsSelect) );
! 3558: if( pE->x.pList==0 || pE->x.pList->nExpr!=1 ){
! 3559: sqlite3ErrorMsg(pParse, "DISTINCT aggregates must have exactly one "
! 3560: "argument");
! 3561: pFunc->iDistinct = -1;
! 3562: }else{
! 3563: KeyInfo *pKeyInfo = keyInfoFromExprList(pParse, pE->x.pList);
! 3564: sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 0,
! 3565: (char*)pKeyInfo, P4_KEYINFO_HANDOFF);
! 3566: }
! 3567: }
! 3568: }
! 3569: }
! 3570:
! 3571: /*
! 3572: ** Invoke the OP_AggFinalize opcode for every aggregate function
! 3573: ** in the AggInfo structure.
! 3574: */
! 3575: static void finalizeAggFunctions(Parse *pParse, AggInfo *pAggInfo){
! 3576: Vdbe *v = pParse->pVdbe;
! 3577: int i;
! 3578: struct AggInfo_func *pF;
! 3579: for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
! 3580: ExprList *pList = pF->pExpr->x.pList;
! 3581: assert( !ExprHasProperty(pF->pExpr, EP_xIsSelect) );
! 3582: sqlite3VdbeAddOp4(v, OP_AggFinal, pF->iMem, pList ? pList->nExpr : 0, 0,
! 3583: (void*)pF->pFunc, P4_FUNCDEF);
! 3584: }
! 3585: }
! 3586:
! 3587: /*
! 3588: ** Update the accumulator memory cells for an aggregate based on
! 3589: ** the current cursor position.
! 3590: */
! 3591: static void updateAccumulator(Parse *pParse, AggInfo *pAggInfo){
! 3592: Vdbe *v = pParse->pVdbe;
! 3593: int i;
! 3594: struct AggInfo_func *pF;
! 3595: struct AggInfo_col *pC;
! 3596:
! 3597: pAggInfo->directMode = 1;
! 3598: sqlite3ExprCacheClear(pParse);
! 3599: for(i=0, pF=pAggInfo->aFunc; i<pAggInfo->nFunc; i++, pF++){
! 3600: int nArg;
! 3601: int addrNext = 0;
! 3602: int regAgg;
! 3603: ExprList *pList = pF->pExpr->x.pList;
! 3604: assert( !ExprHasProperty(pF->pExpr, EP_xIsSelect) );
! 3605: if( pList ){
! 3606: nArg = pList->nExpr;
! 3607: regAgg = sqlite3GetTempRange(pParse, nArg);
! 3608: sqlite3ExprCodeExprList(pParse, pList, regAgg, 1);
! 3609: }else{
! 3610: nArg = 0;
! 3611: regAgg = 0;
! 3612: }
! 3613: if( pF->iDistinct>=0 ){
! 3614: addrNext = sqlite3VdbeMakeLabel(v);
! 3615: assert( nArg==1 );
! 3616: codeDistinct(pParse, pF->iDistinct, addrNext, 1, regAgg);
! 3617: }
! 3618: if( pF->pFunc->flags & SQLITE_FUNC_NEEDCOLL ){
! 3619: CollSeq *pColl = 0;
! 3620: struct ExprList_item *pItem;
! 3621: int j;
! 3622: assert( pList!=0 ); /* pList!=0 if pF->pFunc has NEEDCOLL */
! 3623: for(j=0, pItem=pList->a; !pColl && j<nArg; j++, pItem++){
! 3624: pColl = sqlite3ExprCollSeq(pParse, pItem->pExpr);
! 3625: }
! 3626: if( !pColl ){
! 3627: pColl = pParse->db->pDfltColl;
! 3628: }
! 3629: sqlite3VdbeAddOp4(v, OP_CollSeq, 0, 0, 0, (char *)pColl, P4_COLLSEQ);
! 3630: }
! 3631: sqlite3VdbeAddOp4(v, OP_AggStep, 0, regAgg, pF->iMem,
! 3632: (void*)pF->pFunc, P4_FUNCDEF);
! 3633: sqlite3VdbeChangeP5(v, (u8)nArg);
! 3634: sqlite3ExprCacheAffinityChange(pParse, regAgg, nArg);
! 3635: sqlite3ReleaseTempRange(pParse, regAgg, nArg);
! 3636: if( addrNext ){
! 3637: sqlite3VdbeResolveLabel(v, addrNext);
! 3638: sqlite3ExprCacheClear(pParse);
! 3639: }
! 3640: }
! 3641:
! 3642: /* Before populating the accumulator registers, clear the column cache.
! 3643: ** Otherwise, if any of the required column values are already present
! 3644: ** in registers, sqlite3ExprCode() may use OP_SCopy to copy the value
! 3645: ** to pC->iMem. But by the time the value is used, the original register
! 3646: ** may have been used, invalidating the underlying buffer holding the
! 3647: ** text or blob value. See ticket [883034dcb5].
! 3648: **
! 3649: ** Another solution would be to change the OP_SCopy used to copy cached
! 3650: ** values to an OP_Copy.
! 3651: */
! 3652: sqlite3ExprCacheClear(pParse);
! 3653: for(i=0, pC=pAggInfo->aCol; i<pAggInfo->nAccumulator; i++, pC++){
! 3654: sqlite3ExprCode(pParse, pC->pExpr, pC->iMem);
! 3655: }
! 3656: pAggInfo->directMode = 0;
! 3657: sqlite3ExprCacheClear(pParse);
! 3658: }
! 3659:
! 3660: /*
! 3661: ** Add a single OP_Explain instruction to the VDBE to explain a simple
! 3662: ** count(*) query ("SELECT count(*) FROM pTab").
! 3663: */
! 3664: #ifndef SQLITE_OMIT_EXPLAIN
! 3665: static void explainSimpleCount(
! 3666: Parse *pParse, /* Parse context */
! 3667: Table *pTab, /* Table being queried */
! 3668: Index *pIdx /* Index used to optimize scan, or NULL */
! 3669: ){
! 3670: if( pParse->explain==2 ){
! 3671: char *zEqp = sqlite3MPrintf(pParse->db, "SCAN TABLE %s %s%s(~%d rows)",
! 3672: pTab->zName,
! 3673: pIdx ? "USING COVERING INDEX " : "",
! 3674: pIdx ? pIdx->zName : "",
! 3675: pTab->nRowEst
! 3676: );
! 3677: sqlite3VdbeAddOp4(
! 3678: pParse->pVdbe, OP_Explain, pParse->iSelectId, 0, 0, zEqp, P4_DYNAMIC
! 3679: );
! 3680: }
! 3681: }
! 3682: #else
! 3683: # define explainSimpleCount(a,b,c)
! 3684: #endif
! 3685:
! 3686: /*
! 3687: ** Generate code for the SELECT statement given in the p argument.
! 3688: **
! 3689: ** The results are distributed in various ways depending on the
! 3690: ** contents of the SelectDest structure pointed to by argument pDest
! 3691: ** as follows:
! 3692: **
! 3693: ** pDest->eDest Result
! 3694: ** ------------ -------------------------------------------
! 3695: ** SRT_Output Generate a row of output (using the OP_ResultRow
! 3696: ** opcode) for each row in the result set.
! 3697: **
! 3698: ** SRT_Mem Only valid if the result is a single column.
! 3699: ** Store the first column of the first result row
! 3700: ** in register pDest->iParm then abandon the rest
! 3701: ** of the query. This destination implies "LIMIT 1".
! 3702: **
! 3703: ** SRT_Set The result must be a single column. Store each
! 3704: ** row of result as the key in table pDest->iParm.
! 3705: ** Apply the affinity pDest->affinity before storing
! 3706: ** results. Used to implement "IN (SELECT ...)".
! 3707: **
! 3708: ** SRT_Union Store results as a key in a temporary table pDest->iParm.
! 3709: **
! 3710: ** SRT_Except Remove results from the temporary table pDest->iParm.
! 3711: **
! 3712: ** SRT_Table Store results in temporary table pDest->iParm.
! 3713: ** This is like SRT_EphemTab except that the table
! 3714: ** is assumed to already be open.
! 3715: **
! 3716: ** SRT_EphemTab Create an temporary table pDest->iParm and store
! 3717: ** the result there. The cursor is left open after
! 3718: ** returning. This is like SRT_Table except that
! 3719: ** this destination uses OP_OpenEphemeral to create
! 3720: ** the table first.
! 3721: **
! 3722: ** SRT_Coroutine Generate a co-routine that returns a new row of
! 3723: ** results each time it is invoked. The entry point
! 3724: ** of the co-routine is stored in register pDest->iParm.
! 3725: **
! 3726: ** SRT_Exists Store a 1 in memory cell pDest->iParm if the result
! 3727: ** set is not empty.
! 3728: **
! 3729: ** SRT_Discard Throw the results away. This is used by SELECT
! 3730: ** statements within triggers whose only purpose is
! 3731: ** the side-effects of functions.
! 3732: **
! 3733: ** This routine returns the number of errors. If any errors are
! 3734: ** encountered, then an appropriate error message is left in
! 3735: ** pParse->zErrMsg.
! 3736: **
! 3737: ** This routine does NOT free the Select structure passed in. The
! 3738: ** calling function needs to do that.
! 3739: */
! 3740: int sqlite3Select(
! 3741: Parse *pParse, /* The parser context */
! 3742: Select *p, /* The SELECT statement being coded. */
! 3743: SelectDest *pDest /* What to do with the query results */
! 3744: ){
! 3745: int i, j; /* Loop counters */
! 3746: WhereInfo *pWInfo; /* Return from sqlite3WhereBegin() */
! 3747: Vdbe *v; /* The virtual machine under construction */
! 3748: int isAgg; /* True for select lists like "count(*)" */
! 3749: ExprList *pEList; /* List of columns to extract. */
! 3750: SrcList *pTabList; /* List of tables to select from */
! 3751: Expr *pWhere; /* The WHERE clause. May be NULL */
! 3752: ExprList *pOrderBy; /* The ORDER BY clause. May be NULL */
! 3753: ExprList *pGroupBy; /* The GROUP BY clause. May be NULL */
! 3754: Expr *pHaving; /* The HAVING clause. May be NULL */
! 3755: int isDistinct; /* True if the DISTINCT keyword is present */
! 3756: int distinct; /* Table to use for the distinct set */
! 3757: int rc = 1; /* Value to return from this function */
! 3758: int addrSortIndex; /* Address of an OP_OpenEphemeral instruction */
! 3759: int addrDistinctIndex; /* Address of an OP_OpenEphemeral instruction */
! 3760: AggInfo sAggInfo; /* Information used by aggregate queries */
! 3761: int iEnd; /* Address of the end of the query */
! 3762: sqlite3 *db; /* The database connection */
! 3763:
! 3764: #ifndef SQLITE_OMIT_EXPLAIN
! 3765: int iRestoreSelectId = pParse->iSelectId;
! 3766: pParse->iSelectId = pParse->iNextSelectId++;
! 3767: #endif
! 3768:
! 3769: db = pParse->db;
! 3770: if( p==0 || db->mallocFailed || pParse->nErr ){
! 3771: return 1;
! 3772: }
! 3773: if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;
! 3774: memset(&sAggInfo, 0, sizeof(sAggInfo));
! 3775:
! 3776: if( IgnorableOrderby(pDest) ){
! 3777: assert(pDest->eDest==SRT_Exists || pDest->eDest==SRT_Union ||
! 3778: pDest->eDest==SRT_Except || pDest->eDest==SRT_Discard);
! 3779: /* If ORDER BY makes no difference in the output then neither does
! 3780: ** DISTINCT so it can be removed too. */
! 3781: sqlite3ExprListDelete(db, p->pOrderBy);
! 3782: p->pOrderBy = 0;
! 3783: p->selFlags &= ~SF_Distinct;
! 3784: }
! 3785: sqlite3SelectPrep(pParse, p, 0);
! 3786: pOrderBy = p->pOrderBy;
! 3787: pTabList = p->pSrc;
! 3788: pEList = p->pEList;
! 3789: if( pParse->nErr || db->mallocFailed ){
! 3790: goto select_end;
! 3791: }
! 3792: isAgg = (p->selFlags & SF_Aggregate)!=0;
! 3793: assert( pEList!=0 );
! 3794:
! 3795: /* Begin generating code.
! 3796: */
! 3797: v = sqlite3GetVdbe(pParse);
! 3798: if( v==0 ) goto select_end;
! 3799:
! 3800: /* If writing to memory or generating a set
! 3801: ** only a single column may be output.
! 3802: */
! 3803: #ifndef SQLITE_OMIT_SUBQUERY
! 3804: if( checkForMultiColumnSelectError(pParse, pDest, pEList->nExpr) ){
! 3805: goto select_end;
! 3806: }
! 3807: #endif
! 3808:
! 3809: /* Generate code for all sub-queries in the FROM clause
! 3810: */
! 3811: #if !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW)
! 3812: for(i=0; !p->pPrior && i<pTabList->nSrc; i++){
! 3813: struct SrcList_item *pItem = &pTabList->a[i];
! 3814: SelectDest dest;
! 3815: Select *pSub = pItem->pSelect;
! 3816: int isAggSub;
! 3817:
! 3818: if( pSub==0 ) continue;
! 3819: if( pItem->addrFillSub ){
! 3820: sqlite3VdbeAddOp2(v, OP_Gosub, pItem->regReturn, pItem->addrFillSub);
! 3821: continue;
! 3822: }
! 3823:
! 3824: /* Increment Parse.nHeight by the height of the largest expression
! 3825: ** tree refered to by this, the parent select. The child select
! 3826: ** may contain expression trees of at most
! 3827: ** (SQLITE_MAX_EXPR_DEPTH-Parse.nHeight) height. This is a bit
! 3828: ** more conservative than necessary, but much easier than enforcing
! 3829: ** an exact limit.
! 3830: */
! 3831: pParse->nHeight += sqlite3SelectExprHeight(p);
! 3832:
! 3833: isAggSub = (pSub->selFlags & SF_Aggregate)!=0;
! 3834: if( flattenSubquery(pParse, p, i, isAgg, isAggSub) ){
! 3835: /* This subquery can be absorbed into its parent. */
! 3836: if( isAggSub ){
! 3837: isAgg = 1;
! 3838: p->selFlags |= SF_Aggregate;
! 3839: }
! 3840: i = -1;
! 3841: }else{
! 3842: /* Generate a subroutine that will fill an ephemeral table with
! 3843: ** the content of this subquery. pItem->addrFillSub will point
! 3844: ** to the address of the generated subroutine. pItem->regReturn
! 3845: ** is a register allocated to hold the subroutine return address
! 3846: */
! 3847: int topAddr;
! 3848: int onceAddr = 0;
! 3849: int retAddr;
! 3850: assert( pItem->addrFillSub==0 );
! 3851: pItem->regReturn = ++pParse->nMem;
! 3852: topAddr = sqlite3VdbeAddOp2(v, OP_Integer, 0, pItem->regReturn);
! 3853: pItem->addrFillSub = topAddr+1;
! 3854: VdbeNoopComment((v, "materialize %s", pItem->pTab->zName));
! 3855: if( pItem->isCorrelated==0 ){
! 3856: /* If the subquery is no correlated and if we are not inside of
! 3857: ** a trigger, then we only need to compute the value of the subquery
! 3858: ** once. */
! 3859: onceAddr = sqlite3CodeOnce(pParse);
! 3860: }
! 3861: sqlite3SelectDestInit(&dest, SRT_EphemTab, pItem->iCursor);
! 3862: explainSetInteger(pItem->iSelectId, (u8)pParse->iNextSelectId);
! 3863: sqlite3Select(pParse, pSub, &dest);
! 3864: pItem->pTab->nRowEst = (unsigned)pSub->nSelectRow;
! 3865: if( onceAddr ) sqlite3VdbeJumpHere(v, onceAddr);
! 3866: retAddr = sqlite3VdbeAddOp1(v, OP_Return, pItem->regReturn);
! 3867: VdbeComment((v, "end %s", pItem->pTab->zName));
! 3868: sqlite3VdbeChangeP1(v, topAddr, retAddr);
! 3869: sqlite3ClearTempRegCache(pParse);
! 3870: }
! 3871: if( /*pParse->nErr ||*/ db->mallocFailed ){
! 3872: goto select_end;
! 3873: }
! 3874: pParse->nHeight -= sqlite3SelectExprHeight(p);
! 3875: pTabList = p->pSrc;
! 3876: if( !IgnorableOrderby(pDest) ){
! 3877: pOrderBy = p->pOrderBy;
! 3878: }
! 3879: }
! 3880: pEList = p->pEList;
! 3881: #endif
! 3882: pWhere = p->pWhere;
! 3883: pGroupBy = p->pGroupBy;
! 3884: pHaving = p->pHaving;
! 3885: isDistinct = (p->selFlags & SF_Distinct)!=0;
! 3886:
! 3887: #ifndef SQLITE_OMIT_COMPOUND_SELECT
! 3888: /* If there is are a sequence of queries, do the earlier ones first.
! 3889: */
! 3890: if( p->pPrior ){
! 3891: if( p->pRightmost==0 ){
! 3892: Select *pLoop, *pRight = 0;
! 3893: int cnt = 0;
! 3894: int mxSelect;
! 3895: for(pLoop=p; pLoop; pLoop=pLoop->pPrior, cnt++){
! 3896: pLoop->pRightmost = p;
! 3897: pLoop->pNext = pRight;
! 3898: pRight = pLoop;
! 3899: }
! 3900: mxSelect = db->aLimit[SQLITE_LIMIT_COMPOUND_SELECT];
! 3901: if( mxSelect && cnt>mxSelect ){
! 3902: sqlite3ErrorMsg(pParse, "too many terms in compound SELECT");
! 3903: goto select_end;
! 3904: }
! 3905: }
! 3906: rc = multiSelect(pParse, p, pDest);
! 3907: explainSetInteger(pParse->iSelectId, iRestoreSelectId);
! 3908: return rc;
! 3909: }
! 3910: #endif
! 3911:
! 3912: /* If there is both a GROUP BY and an ORDER BY clause and they are
! 3913: ** identical, then disable the ORDER BY clause since the GROUP BY
! 3914: ** will cause elements to come out in the correct order. This is
! 3915: ** an optimization - the correct answer should result regardless.
! 3916: ** Use the SQLITE_GroupByOrder flag with SQLITE_TESTCTRL_OPTIMIZER
! 3917: ** to disable this optimization for testing purposes.
! 3918: */
! 3919: if( sqlite3ExprListCompare(p->pGroupBy, pOrderBy)==0
! 3920: && (db->flags & SQLITE_GroupByOrder)==0 ){
! 3921: pOrderBy = 0;
! 3922: }
! 3923:
! 3924: /* If the query is DISTINCT with an ORDER BY but is not an aggregate, and
! 3925: ** if the select-list is the same as the ORDER BY list, then this query
! 3926: ** can be rewritten as a GROUP BY. In other words, this:
! 3927: **
! 3928: ** SELECT DISTINCT xyz FROM ... ORDER BY xyz
! 3929: **
! 3930: ** is transformed to:
! 3931: **
! 3932: ** SELECT xyz FROM ... GROUP BY xyz
! 3933: **
! 3934: ** The second form is preferred as a single index (or temp-table) may be
! 3935: ** used for both the ORDER BY and DISTINCT processing. As originally
! 3936: ** written the query must use a temp-table for at least one of the ORDER
! 3937: ** BY and DISTINCT, and an index or separate temp-table for the other.
! 3938: */
! 3939: if( (p->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct
! 3940: && sqlite3ExprListCompare(pOrderBy, p->pEList)==0
! 3941: ){
! 3942: p->selFlags &= ~SF_Distinct;
! 3943: p->pGroupBy = sqlite3ExprListDup(db, p->pEList, 0);
! 3944: pGroupBy = p->pGroupBy;
! 3945: pOrderBy = 0;
! 3946: }
! 3947:
! 3948: /* If there is an ORDER BY clause, then this sorting
! 3949: ** index might end up being unused if the data can be
! 3950: ** extracted in pre-sorted order. If that is the case, then the
! 3951: ** OP_OpenEphemeral instruction will be changed to an OP_Noop once
! 3952: ** we figure out that the sorting index is not needed. The addrSortIndex
! 3953: ** variable is used to facilitate that change.
! 3954: */
! 3955: if( pOrderBy ){
! 3956: KeyInfo *pKeyInfo;
! 3957: pKeyInfo = keyInfoFromExprList(pParse, pOrderBy);
! 3958: pOrderBy->iECursor = pParse->nTab++;
! 3959: p->addrOpenEphm[2] = addrSortIndex =
! 3960: sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
! 3961: pOrderBy->iECursor, pOrderBy->nExpr+2, 0,
! 3962: (char*)pKeyInfo, P4_KEYINFO_HANDOFF);
! 3963: }else{
! 3964: addrSortIndex = -1;
! 3965: }
! 3966:
! 3967: /* If the output is destined for a temporary table, open that table.
! 3968: */
! 3969: if( pDest->eDest==SRT_EphemTab ){
! 3970: sqlite3VdbeAddOp2(v, OP_OpenEphemeral, pDest->iParm, pEList->nExpr);
! 3971: }
! 3972:
! 3973: /* Set the limiter.
! 3974: */
! 3975: iEnd = sqlite3VdbeMakeLabel(v);
! 3976: p->nSelectRow = (double)LARGEST_INT64;
! 3977: computeLimitRegisters(pParse, p, iEnd);
! 3978: if( p->iLimit==0 && addrSortIndex>=0 ){
! 3979: sqlite3VdbeGetOp(v, addrSortIndex)->opcode = OP_SorterOpen;
! 3980: p->selFlags |= SF_UseSorter;
! 3981: }
! 3982:
! 3983: /* Open a virtual index to use for the distinct set.
! 3984: */
! 3985: if( p->selFlags & SF_Distinct ){
! 3986: KeyInfo *pKeyInfo;
! 3987: distinct = pParse->nTab++;
! 3988: pKeyInfo = keyInfoFromExprList(pParse, p->pEList);
! 3989: addrDistinctIndex = sqlite3VdbeAddOp4(v, OP_OpenEphemeral, distinct, 0, 0,
! 3990: (char*)pKeyInfo, P4_KEYINFO_HANDOFF);
! 3991: sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
! 3992: }else{
! 3993: distinct = addrDistinctIndex = -1;
! 3994: }
! 3995:
! 3996: /* Aggregate and non-aggregate queries are handled differently */
! 3997: if( !isAgg && pGroupBy==0 ){
! 3998: ExprList *pDist = (isDistinct ? p->pEList : 0);
! 3999:
! 4000: /* Begin the database scan. */
! 4001: pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pOrderBy, pDist, 0);
! 4002: if( pWInfo==0 ) goto select_end;
! 4003: if( pWInfo->nRowOut < p->nSelectRow ) p->nSelectRow = pWInfo->nRowOut;
! 4004:
! 4005: /* If sorting index that was created by a prior OP_OpenEphemeral
! 4006: ** instruction ended up not being needed, then change the OP_OpenEphemeral
! 4007: ** into an OP_Noop.
! 4008: */
! 4009: if( addrSortIndex>=0 && pOrderBy==0 ){
! 4010: sqlite3VdbeChangeToNoop(v, addrSortIndex);
! 4011: p->addrOpenEphm[2] = -1;
! 4012: }
! 4013:
! 4014: if( pWInfo->eDistinct ){
! 4015: VdbeOp *pOp; /* No longer required OpenEphemeral instr. */
! 4016:
! 4017: assert( addrDistinctIndex>=0 );
! 4018: pOp = sqlite3VdbeGetOp(v, addrDistinctIndex);
! 4019:
! 4020: assert( isDistinct );
! 4021: assert( pWInfo->eDistinct==WHERE_DISTINCT_ORDERED
! 4022: || pWInfo->eDistinct==WHERE_DISTINCT_UNIQUE
! 4023: );
! 4024: distinct = -1;
! 4025: if( pWInfo->eDistinct==WHERE_DISTINCT_ORDERED ){
! 4026: int iJump;
! 4027: int iExpr;
! 4028: int iFlag = ++pParse->nMem;
! 4029: int iBase = pParse->nMem+1;
! 4030: int iBase2 = iBase + pEList->nExpr;
! 4031: pParse->nMem += (pEList->nExpr*2);
! 4032:
! 4033: /* Change the OP_OpenEphemeral coded earlier to an OP_Integer. The
! 4034: ** OP_Integer initializes the "first row" flag. */
! 4035: pOp->opcode = OP_Integer;
! 4036: pOp->p1 = 1;
! 4037: pOp->p2 = iFlag;
! 4038:
! 4039: sqlite3ExprCodeExprList(pParse, pEList, iBase, 1);
! 4040: iJump = sqlite3VdbeCurrentAddr(v) + 1 + pEList->nExpr + 1 + 1;
! 4041: sqlite3VdbeAddOp2(v, OP_If, iFlag, iJump-1);
! 4042: for(iExpr=0; iExpr<pEList->nExpr; iExpr++){
! 4043: CollSeq *pColl = sqlite3ExprCollSeq(pParse, pEList->a[iExpr].pExpr);
! 4044: sqlite3VdbeAddOp3(v, OP_Ne, iBase+iExpr, iJump, iBase2+iExpr);
! 4045: sqlite3VdbeChangeP4(v, -1, (const char *)pColl, P4_COLLSEQ);
! 4046: sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
! 4047: }
! 4048: sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iContinue);
! 4049:
! 4050: sqlite3VdbeAddOp2(v, OP_Integer, 0, iFlag);
! 4051: assert( sqlite3VdbeCurrentAddr(v)==iJump );
! 4052: sqlite3VdbeAddOp3(v, OP_Move, iBase, iBase2, pEList->nExpr);
! 4053: }else{
! 4054: pOp->opcode = OP_Noop;
! 4055: }
! 4056: }
! 4057:
! 4058: /* Use the standard inner loop. */
! 4059: selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, pDest,
! 4060: pWInfo->iContinue, pWInfo->iBreak);
! 4061:
! 4062: /* End the database scan loop.
! 4063: */
! 4064: sqlite3WhereEnd(pWInfo);
! 4065: }else{
! 4066: /* This is the processing for aggregate queries */
! 4067: NameContext sNC; /* Name context for processing aggregate information */
! 4068: int iAMem; /* First Mem address for storing current GROUP BY */
! 4069: int iBMem; /* First Mem address for previous GROUP BY */
! 4070: int iUseFlag; /* Mem address holding flag indicating that at least
! 4071: ** one row of the input to the aggregator has been
! 4072: ** processed */
! 4073: int iAbortFlag; /* Mem address which causes query abort if positive */
! 4074: int groupBySort; /* Rows come from source in GROUP BY order */
! 4075: int addrEnd; /* End of processing for this SELECT */
! 4076: int sortPTab = 0; /* Pseudotable used to decode sorting results */
! 4077: int sortOut = 0; /* Output register from the sorter */
! 4078:
! 4079: /* Remove any and all aliases between the result set and the
! 4080: ** GROUP BY clause.
! 4081: */
! 4082: if( pGroupBy ){
! 4083: int k; /* Loop counter */
! 4084: struct ExprList_item *pItem; /* For looping over expression in a list */
! 4085:
! 4086: for(k=p->pEList->nExpr, pItem=p->pEList->a; k>0; k--, pItem++){
! 4087: pItem->iAlias = 0;
! 4088: }
! 4089: for(k=pGroupBy->nExpr, pItem=pGroupBy->a; k>0; k--, pItem++){
! 4090: pItem->iAlias = 0;
! 4091: }
! 4092: if( p->nSelectRow>(double)100 ) p->nSelectRow = (double)100;
! 4093: }else{
! 4094: p->nSelectRow = (double)1;
! 4095: }
! 4096:
! 4097:
! 4098: /* Create a label to jump to when we want to abort the query */
! 4099: addrEnd = sqlite3VdbeMakeLabel(v);
! 4100:
! 4101: /* Convert TK_COLUMN nodes into TK_AGG_COLUMN and make entries in
! 4102: ** sAggInfo for all TK_AGG_FUNCTION nodes in expressions of the
! 4103: ** SELECT statement.
! 4104: */
! 4105: memset(&sNC, 0, sizeof(sNC));
! 4106: sNC.pParse = pParse;
! 4107: sNC.pSrcList = pTabList;
! 4108: sNC.pAggInfo = &sAggInfo;
! 4109: sAggInfo.nSortingColumn = pGroupBy ? pGroupBy->nExpr+1 : 0;
! 4110: sAggInfo.pGroupBy = pGroupBy;
! 4111: sqlite3ExprAnalyzeAggList(&sNC, pEList);
! 4112: sqlite3ExprAnalyzeAggList(&sNC, pOrderBy);
! 4113: if( pHaving ){
! 4114: sqlite3ExprAnalyzeAggregates(&sNC, pHaving);
! 4115: }
! 4116: sAggInfo.nAccumulator = sAggInfo.nColumn;
! 4117: for(i=0; i<sAggInfo.nFunc; i++){
! 4118: assert( !ExprHasProperty(sAggInfo.aFunc[i].pExpr, EP_xIsSelect) );
! 4119: sqlite3ExprAnalyzeAggList(&sNC, sAggInfo.aFunc[i].pExpr->x.pList);
! 4120: }
! 4121: if( db->mallocFailed ) goto select_end;
! 4122:
! 4123: /* Processing for aggregates with GROUP BY is very different and
! 4124: ** much more complex than aggregates without a GROUP BY.
! 4125: */
! 4126: if( pGroupBy ){
! 4127: KeyInfo *pKeyInfo; /* Keying information for the group by clause */
! 4128: int j1; /* A-vs-B comparision jump */
! 4129: int addrOutputRow; /* Start of subroutine that outputs a result row */
! 4130: int regOutputRow; /* Return address register for output subroutine */
! 4131: int addrSetAbort; /* Set the abort flag and return */
! 4132: int addrTopOfLoop; /* Top of the input loop */
! 4133: int addrSortingIdx; /* The OP_OpenEphemeral for the sorting index */
! 4134: int addrReset; /* Subroutine for resetting the accumulator */
! 4135: int regReset; /* Return address register for reset subroutine */
! 4136:
! 4137: /* If there is a GROUP BY clause we might need a sorting index to
! 4138: ** implement it. Allocate that sorting index now. If it turns out
! 4139: ** that we do not need it after all, the OP_SorterOpen instruction
! 4140: ** will be converted into a Noop.
! 4141: */
! 4142: sAggInfo.sortingIdx = pParse->nTab++;
! 4143: pKeyInfo = keyInfoFromExprList(pParse, pGroupBy);
! 4144: addrSortingIdx = sqlite3VdbeAddOp4(v, OP_SorterOpen,
! 4145: sAggInfo.sortingIdx, sAggInfo.nSortingColumn,
! 4146: 0, (char*)pKeyInfo, P4_KEYINFO_HANDOFF);
! 4147:
! 4148: /* Initialize memory locations used by GROUP BY aggregate processing
! 4149: */
! 4150: iUseFlag = ++pParse->nMem;
! 4151: iAbortFlag = ++pParse->nMem;
! 4152: regOutputRow = ++pParse->nMem;
! 4153: addrOutputRow = sqlite3VdbeMakeLabel(v);
! 4154: regReset = ++pParse->nMem;
! 4155: addrReset = sqlite3VdbeMakeLabel(v);
! 4156: iAMem = pParse->nMem + 1;
! 4157: pParse->nMem += pGroupBy->nExpr;
! 4158: iBMem = pParse->nMem + 1;
! 4159: pParse->nMem += pGroupBy->nExpr;
! 4160: sqlite3VdbeAddOp2(v, OP_Integer, 0, iAbortFlag);
! 4161: VdbeComment((v, "clear abort flag"));
! 4162: sqlite3VdbeAddOp2(v, OP_Integer, 0, iUseFlag);
! 4163: VdbeComment((v, "indicate accumulator empty"));
! 4164: sqlite3VdbeAddOp3(v, OP_Null, 0, iAMem, iAMem+pGroupBy->nExpr-1);
! 4165:
! 4166: /* Begin a loop that will extract all source rows in GROUP BY order.
! 4167: ** This might involve two separate loops with an OP_Sort in between, or
! 4168: ** it might be a single loop that uses an index to extract information
! 4169: ** in the right order to begin with.
! 4170: */
! 4171: sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
! 4172: pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pGroupBy, 0, 0);
! 4173: if( pWInfo==0 ) goto select_end;
! 4174: if( pGroupBy==0 ){
! 4175: /* The optimizer is able to deliver rows in group by order so
! 4176: ** we do not have to sort. The OP_OpenEphemeral table will be
! 4177: ** cancelled later because we still need to use the pKeyInfo
! 4178: */
! 4179: pGroupBy = p->pGroupBy;
! 4180: groupBySort = 0;
! 4181: }else{
! 4182: /* Rows are coming out in undetermined order. We have to push
! 4183: ** each row into a sorting index, terminate the first loop,
! 4184: ** then loop over the sorting index in order to get the output
! 4185: ** in sorted order
! 4186: */
! 4187: int regBase;
! 4188: int regRecord;
! 4189: int nCol;
! 4190: int nGroupBy;
! 4191:
! 4192: explainTempTable(pParse,
! 4193: isDistinct && !(p->selFlags&SF_Distinct)?"DISTINCT":"GROUP BY");
! 4194:
! 4195: groupBySort = 1;
! 4196: nGroupBy = pGroupBy->nExpr;
! 4197: nCol = nGroupBy + 1;
! 4198: j = nGroupBy+1;
! 4199: for(i=0; i<sAggInfo.nColumn; i++){
! 4200: if( sAggInfo.aCol[i].iSorterColumn>=j ){
! 4201: nCol++;
! 4202: j++;
! 4203: }
! 4204: }
! 4205: regBase = sqlite3GetTempRange(pParse, nCol);
! 4206: sqlite3ExprCacheClear(pParse);
! 4207: sqlite3ExprCodeExprList(pParse, pGroupBy, regBase, 0);
! 4208: sqlite3VdbeAddOp2(v, OP_Sequence, sAggInfo.sortingIdx,regBase+nGroupBy);
! 4209: j = nGroupBy+1;
! 4210: for(i=0; i<sAggInfo.nColumn; i++){
! 4211: struct AggInfo_col *pCol = &sAggInfo.aCol[i];
! 4212: if( pCol->iSorterColumn>=j ){
! 4213: int r1 = j + regBase;
! 4214: int r2;
! 4215:
! 4216: r2 = sqlite3ExprCodeGetColumn(pParse,
! 4217: pCol->pTab, pCol->iColumn, pCol->iTable, r1);
! 4218: if( r1!=r2 ){
! 4219: sqlite3VdbeAddOp2(v, OP_SCopy, r2, r1);
! 4220: }
! 4221: j++;
! 4222: }
! 4223: }
! 4224: regRecord = sqlite3GetTempReg(pParse);
! 4225: sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regRecord);
! 4226: sqlite3VdbeAddOp2(v, OP_SorterInsert, sAggInfo.sortingIdx, regRecord);
! 4227: sqlite3ReleaseTempReg(pParse, regRecord);
! 4228: sqlite3ReleaseTempRange(pParse, regBase, nCol);
! 4229: sqlite3WhereEnd(pWInfo);
! 4230: sAggInfo.sortingIdxPTab = sortPTab = pParse->nTab++;
! 4231: sortOut = sqlite3GetTempReg(pParse);
! 4232: sqlite3VdbeAddOp3(v, OP_OpenPseudo, sortPTab, sortOut, nCol);
! 4233: sqlite3VdbeAddOp2(v, OP_SorterSort, sAggInfo.sortingIdx, addrEnd);
! 4234: VdbeComment((v, "GROUP BY sort"));
! 4235: sAggInfo.useSortingIdx = 1;
! 4236: sqlite3ExprCacheClear(pParse);
! 4237: }
! 4238:
! 4239: /* Evaluate the current GROUP BY terms and store in b0, b1, b2...
! 4240: ** (b0 is memory location iBMem+0, b1 is iBMem+1, and so forth)
! 4241: ** Then compare the current GROUP BY terms against the GROUP BY terms
! 4242: ** from the previous row currently stored in a0, a1, a2...
! 4243: */
! 4244: addrTopOfLoop = sqlite3VdbeCurrentAddr(v);
! 4245: sqlite3ExprCacheClear(pParse);
! 4246: if( groupBySort ){
! 4247: sqlite3VdbeAddOp2(v, OP_SorterData, sAggInfo.sortingIdx, sortOut);
! 4248: }
! 4249: for(j=0; j<pGroupBy->nExpr; j++){
! 4250: if( groupBySort ){
! 4251: sqlite3VdbeAddOp3(v, OP_Column, sortPTab, j, iBMem+j);
! 4252: if( j==0 ) sqlite3VdbeChangeP5(v, OPFLAG_CLEARCACHE);
! 4253: }else{
! 4254: sAggInfo.directMode = 1;
! 4255: sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr, iBMem+j);
! 4256: }
! 4257: }
! 4258: sqlite3VdbeAddOp4(v, OP_Compare, iAMem, iBMem, pGroupBy->nExpr,
! 4259: (char*)pKeyInfo, P4_KEYINFO);
! 4260: j1 = sqlite3VdbeCurrentAddr(v);
! 4261: sqlite3VdbeAddOp3(v, OP_Jump, j1+1, 0, j1+1);
! 4262:
! 4263: /* Generate code that runs whenever the GROUP BY changes.
! 4264: ** Changes in the GROUP BY are detected by the previous code
! 4265: ** block. If there were no changes, this block is skipped.
! 4266: **
! 4267: ** This code copies current group by terms in b0,b1,b2,...
! 4268: ** over to a0,a1,a2. It then calls the output subroutine
! 4269: ** and resets the aggregate accumulator registers in preparation
! 4270: ** for the next GROUP BY batch.
! 4271: */
! 4272: sqlite3ExprCodeMove(pParse, iBMem, iAMem, pGroupBy->nExpr);
! 4273: sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow);
! 4274: VdbeComment((v, "output one row"));
! 4275: sqlite3VdbeAddOp2(v, OP_IfPos, iAbortFlag, addrEnd);
! 4276: VdbeComment((v, "check abort flag"));
! 4277: sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
! 4278: VdbeComment((v, "reset accumulator"));
! 4279:
! 4280: /* Update the aggregate accumulators based on the content of
! 4281: ** the current row
! 4282: */
! 4283: sqlite3VdbeJumpHere(v, j1);
! 4284: updateAccumulator(pParse, &sAggInfo);
! 4285: sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag);
! 4286: VdbeComment((v, "indicate data in accumulator"));
! 4287:
! 4288: /* End of the loop
! 4289: */
! 4290: if( groupBySort ){
! 4291: sqlite3VdbeAddOp2(v, OP_SorterNext, sAggInfo.sortingIdx, addrTopOfLoop);
! 4292: }else{
! 4293: sqlite3WhereEnd(pWInfo);
! 4294: sqlite3VdbeChangeToNoop(v, addrSortingIdx);
! 4295: }
! 4296:
! 4297: /* Output the final row of result
! 4298: */
! 4299: sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow);
! 4300: VdbeComment((v, "output final row"));
! 4301:
! 4302: /* Jump over the subroutines
! 4303: */
! 4304: sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEnd);
! 4305:
! 4306: /* Generate a subroutine that outputs a single row of the result
! 4307: ** set. This subroutine first looks at the iUseFlag. If iUseFlag
! 4308: ** is less than or equal to zero, the subroutine is a no-op. If
! 4309: ** the processing calls for the query to abort, this subroutine
! 4310: ** increments the iAbortFlag memory location before returning in
! 4311: ** order to signal the caller to abort.
! 4312: */
! 4313: addrSetAbort = sqlite3VdbeCurrentAddr(v);
! 4314: sqlite3VdbeAddOp2(v, OP_Integer, 1, iAbortFlag);
! 4315: VdbeComment((v, "set abort flag"));
! 4316: sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
! 4317: sqlite3VdbeResolveLabel(v, addrOutputRow);
! 4318: addrOutputRow = sqlite3VdbeCurrentAddr(v);
! 4319: sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2);
! 4320: VdbeComment((v, "Groupby result generator entry point"));
! 4321: sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
! 4322: finalizeAggFunctions(pParse, &sAggInfo);
! 4323: sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
! 4324: selectInnerLoop(pParse, p, p->pEList, 0, 0, pOrderBy,
! 4325: distinct, pDest,
! 4326: addrOutputRow+1, addrSetAbort);
! 4327: sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
! 4328: VdbeComment((v, "end groupby result generator"));
! 4329:
! 4330: /* Generate a subroutine that will reset the group-by accumulator
! 4331: */
! 4332: sqlite3VdbeResolveLabel(v, addrReset);
! 4333: resetAccumulator(pParse, &sAggInfo);
! 4334: sqlite3VdbeAddOp1(v, OP_Return, regReset);
! 4335:
! 4336: } /* endif pGroupBy. Begin aggregate queries without GROUP BY: */
! 4337: else {
! 4338: ExprList *pDel = 0;
! 4339: #ifndef SQLITE_OMIT_BTREECOUNT
! 4340: Table *pTab;
! 4341: if( (pTab = isSimpleCount(p, &sAggInfo))!=0 ){
! 4342: /* If isSimpleCount() returns a pointer to a Table structure, then
! 4343: ** the SQL statement is of the form:
! 4344: **
! 4345: ** SELECT count(*) FROM <tbl>
! 4346: **
! 4347: ** where the Table structure returned represents table <tbl>.
! 4348: **
! 4349: ** This statement is so common that it is optimized specially. The
! 4350: ** OP_Count instruction is executed either on the intkey table that
! 4351: ** contains the data for table <tbl> or on one of its indexes. It
! 4352: ** is better to execute the op on an index, as indexes are almost
! 4353: ** always spread across less pages than their corresponding tables.
! 4354: */
! 4355: const int iDb = sqlite3SchemaToIndex(pParse->db, pTab->pSchema);
! 4356: const int iCsr = pParse->nTab++; /* Cursor to scan b-tree */
! 4357: Index *pIdx; /* Iterator variable */
! 4358: KeyInfo *pKeyInfo = 0; /* Keyinfo for scanned index */
! 4359: Index *pBest = 0; /* Best index found so far */
! 4360: int iRoot = pTab->tnum; /* Root page of scanned b-tree */
! 4361:
! 4362: sqlite3CodeVerifySchema(pParse, iDb);
! 4363: sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
! 4364:
! 4365: /* Search for the index that has the least amount of columns. If
! 4366: ** there is such an index, and it has less columns than the table
! 4367: ** does, then we can assume that it consumes less space on disk and
! 4368: ** will therefore be cheaper to scan to determine the query result.
! 4369: ** In this case set iRoot to the root page number of the index b-tree
! 4370: ** and pKeyInfo to the KeyInfo structure required to navigate the
! 4371: ** index.
! 4372: **
! 4373: ** (2011-04-15) Do not do a full scan of an unordered index.
! 4374: **
! 4375: ** In practice the KeyInfo structure will not be used. It is only
! 4376: ** passed to keep OP_OpenRead happy.
! 4377: */
! 4378: for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
! 4379: if( pIdx->bUnordered==0 && (!pBest || pIdx->nColumn<pBest->nColumn) ){
! 4380: pBest = pIdx;
! 4381: }
! 4382: }
! 4383: if( pBest && pBest->nColumn<pTab->nCol ){
! 4384: iRoot = pBest->tnum;
! 4385: pKeyInfo = sqlite3IndexKeyinfo(pParse, pBest);
! 4386: }
! 4387:
! 4388: /* Open a read-only cursor, execute the OP_Count, close the cursor. */
! 4389: sqlite3VdbeAddOp3(v, OP_OpenRead, iCsr, iRoot, iDb);
! 4390: if( pKeyInfo ){
! 4391: sqlite3VdbeChangeP4(v, -1, (char *)pKeyInfo, P4_KEYINFO_HANDOFF);
! 4392: }
! 4393: sqlite3VdbeAddOp2(v, OP_Count, iCsr, sAggInfo.aFunc[0].iMem);
! 4394: sqlite3VdbeAddOp1(v, OP_Close, iCsr);
! 4395: explainSimpleCount(pParse, pTab, pBest);
! 4396: }else
! 4397: #endif /* SQLITE_OMIT_BTREECOUNT */
! 4398: {
! 4399: /* Check if the query is of one of the following forms:
! 4400: **
! 4401: ** SELECT min(x) FROM ...
! 4402: ** SELECT max(x) FROM ...
! 4403: **
! 4404: ** If it is, then ask the code in where.c to attempt to sort results
! 4405: ** as if there was an "ORDER ON x" or "ORDER ON x DESC" clause.
! 4406: ** If where.c is able to produce results sorted in this order, then
! 4407: ** add vdbe code to break out of the processing loop after the
! 4408: ** first iteration (since the first iteration of the loop is
! 4409: ** guaranteed to operate on the row with the minimum or maximum
! 4410: ** value of x, the only row required).
! 4411: **
! 4412: ** A special flag must be passed to sqlite3WhereBegin() to slightly
! 4413: ** modify behaviour as follows:
! 4414: **
! 4415: ** + If the query is a "SELECT min(x)", then the loop coded by
! 4416: ** where.c should not iterate over any values with a NULL value
! 4417: ** for x.
! 4418: **
! 4419: ** + The optimizer code in where.c (the thing that decides which
! 4420: ** index or indices to use) should place a different priority on
! 4421: ** satisfying the 'ORDER BY' clause than it does in other cases.
! 4422: ** Refer to code and comments in where.c for details.
! 4423: */
! 4424: ExprList *pMinMax = 0;
! 4425: u8 flag = minMaxQuery(p);
! 4426: if( flag ){
! 4427: assert( !ExprHasProperty(p->pEList->a[0].pExpr, EP_xIsSelect) );
! 4428: pMinMax = sqlite3ExprListDup(db, p->pEList->a[0].pExpr->x.pList,0);
! 4429: pDel = pMinMax;
! 4430: if( pMinMax && !db->mallocFailed ){
! 4431: pMinMax->a[0].sortOrder = flag!=WHERE_ORDERBY_MIN ?1:0;
! 4432: pMinMax->a[0].pExpr->op = TK_COLUMN;
! 4433: }
! 4434: }
! 4435:
! 4436: /* This case runs if the aggregate has no GROUP BY clause. The
! 4437: ** processing is much simpler since there is only a single row
! 4438: ** of output.
! 4439: */
! 4440: resetAccumulator(pParse, &sAggInfo);
! 4441: pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pMinMax, 0, flag);
! 4442: if( pWInfo==0 ){
! 4443: sqlite3ExprListDelete(db, pDel);
! 4444: goto select_end;
! 4445: }
! 4446: updateAccumulator(pParse, &sAggInfo);
! 4447: if( !pMinMax && flag ){
! 4448: sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iBreak);
! 4449: VdbeComment((v, "%s() by index",
! 4450: (flag==WHERE_ORDERBY_MIN?"min":"max")));
! 4451: }
! 4452: sqlite3WhereEnd(pWInfo);
! 4453: finalizeAggFunctions(pParse, &sAggInfo);
! 4454: }
! 4455:
! 4456: pOrderBy = 0;
! 4457: sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);
! 4458: selectInnerLoop(pParse, p, p->pEList, 0, 0, 0, -1,
! 4459: pDest, addrEnd, addrEnd);
! 4460: sqlite3ExprListDelete(db, pDel);
! 4461: }
! 4462: sqlite3VdbeResolveLabel(v, addrEnd);
! 4463:
! 4464: } /* endif aggregate query */
! 4465:
! 4466: if( distinct>=0 ){
! 4467: explainTempTable(pParse, "DISTINCT");
! 4468: }
! 4469:
! 4470: /* If there is an ORDER BY clause, then we need to sort the results
! 4471: ** and send them to the callback one by one.
! 4472: */
! 4473: if( pOrderBy ){
! 4474: explainTempTable(pParse, "ORDER BY");
! 4475: generateSortTail(pParse, p, v, pEList->nExpr, pDest);
! 4476: }
! 4477:
! 4478: /* Jump here to skip this query
! 4479: */
! 4480: sqlite3VdbeResolveLabel(v, iEnd);
! 4481:
! 4482: /* The SELECT was successfully coded. Set the return code to 0
! 4483: ** to indicate no errors.
! 4484: */
! 4485: rc = 0;
! 4486:
! 4487: /* Control jumps to here if an error is encountered above, or upon
! 4488: ** successful coding of the SELECT.
! 4489: */
! 4490: select_end:
! 4491: explainSetInteger(pParse->iSelectId, iRestoreSelectId);
! 4492:
! 4493: /* Identify column names if results of the SELECT are to be output.
! 4494: */
! 4495: if( rc==SQLITE_OK && pDest->eDest==SRT_Output ){
! 4496: generateColumnNames(pParse, pTabList, pEList);
! 4497: }
! 4498:
! 4499: sqlite3DbFree(db, sAggInfo.aCol);
! 4500: sqlite3DbFree(db, sAggInfo.aFunc);
! 4501: return rc;
! 4502: }
! 4503:
! 4504: #if defined(SQLITE_ENABLE_TREE_EXPLAIN)
! 4505: /*
! 4506: ** Generate a human-readable description of a the Select object.
! 4507: */
! 4508: static void explainOneSelect(Vdbe *pVdbe, Select *p){
! 4509: sqlite3ExplainPrintf(pVdbe, "SELECT ");
! 4510: if( p->selFlags & (SF_Distinct|SF_Aggregate) ){
! 4511: if( p->selFlags & SF_Distinct ){
! 4512: sqlite3ExplainPrintf(pVdbe, "DISTINCT ");
! 4513: }
! 4514: if( p->selFlags & SF_Aggregate ){
! 4515: sqlite3ExplainPrintf(pVdbe, "agg_flag ");
! 4516: }
! 4517: sqlite3ExplainNL(pVdbe);
! 4518: sqlite3ExplainPrintf(pVdbe, " ");
! 4519: }
! 4520: sqlite3ExplainExprList(pVdbe, p->pEList);
! 4521: sqlite3ExplainNL(pVdbe);
! 4522: if( p->pSrc && p->pSrc->nSrc ){
! 4523: int i;
! 4524: sqlite3ExplainPrintf(pVdbe, "FROM ");
! 4525: sqlite3ExplainPush(pVdbe);
! 4526: for(i=0; i<p->pSrc->nSrc; i++){
! 4527: struct SrcList_item *pItem = &p->pSrc->a[i];
! 4528: sqlite3ExplainPrintf(pVdbe, "{%d,*} = ", pItem->iCursor);
! 4529: if( pItem->pSelect ){
! 4530: sqlite3ExplainSelect(pVdbe, pItem->pSelect);
! 4531: if( pItem->pTab ){
! 4532: sqlite3ExplainPrintf(pVdbe, " (tabname=%s)", pItem->pTab->zName);
! 4533: }
! 4534: }else if( pItem->zName ){
! 4535: sqlite3ExplainPrintf(pVdbe, "%s", pItem->zName);
! 4536: }
! 4537: if( pItem->zAlias ){
! 4538: sqlite3ExplainPrintf(pVdbe, " (AS %s)", pItem->zAlias);
! 4539: }
! 4540: if( pItem->jointype & JT_LEFT ){
! 4541: sqlite3ExplainPrintf(pVdbe, " LEFT-JOIN");
! 4542: }
! 4543: sqlite3ExplainNL(pVdbe);
! 4544: }
! 4545: sqlite3ExplainPop(pVdbe);
! 4546: }
! 4547: if( p->pWhere ){
! 4548: sqlite3ExplainPrintf(pVdbe, "WHERE ");
! 4549: sqlite3ExplainExpr(pVdbe, p->pWhere);
! 4550: sqlite3ExplainNL(pVdbe);
! 4551: }
! 4552: if( p->pGroupBy ){
! 4553: sqlite3ExplainPrintf(pVdbe, "GROUPBY ");
! 4554: sqlite3ExplainExprList(pVdbe, p->pGroupBy);
! 4555: sqlite3ExplainNL(pVdbe);
! 4556: }
! 4557: if( p->pHaving ){
! 4558: sqlite3ExplainPrintf(pVdbe, "HAVING ");
! 4559: sqlite3ExplainExpr(pVdbe, p->pHaving);
! 4560: sqlite3ExplainNL(pVdbe);
! 4561: }
! 4562: if( p->pOrderBy ){
! 4563: sqlite3ExplainPrintf(pVdbe, "ORDERBY ");
! 4564: sqlite3ExplainExprList(pVdbe, p->pOrderBy);
! 4565: sqlite3ExplainNL(pVdbe);
! 4566: }
! 4567: if( p->pLimit ){
! 4568: sqlite3ExplainPrintf(pVdbe, "LIMIT ");
! 4569: sqlite3ExplainExpr(pVdbe, p->pLimit);
! 4570: sqlite3ExplainNL(pVdbe);
! 4571: }
! 4572: if( p->pOffset ){
! 4573: sqlite3ExplainPrintf(pVdbe, "OFFSET ");
! 4574: sqlite3ExplainExpr(pVdbe, p->pOffset);
! 4575: sqlite3ExplainNL(pVdbe);
! 4576: }
! 4577: }
! 4578: void sqlite3ExplainSelect(Vdbe *pVdbe, Select *p){
! 4579: if( p==0 ){
! 4580: sqlite3ExplainPrintf(pVdbe, "(null-select)");
! 4581: return;
! 4582: }
! 4583: while( p->pPrior ) p = p->pPrior;
! 4584: sqlite3ExplainPush(pVdbe);
! 4585: while( p ){
! 4586: explainOneSelect(pVdbe, p);
! 4587: p = p->pNext;
! 4588: if( p==0 ) break;
! 4589: sqlite3ExplainNL(pVdbe);
! 4590: sqlite3ExplainPrintf(pVdbe, "%s\n", selectOpName(p->op));
! 4591: }
! 4592: sqlite3ExplainPrintf(pVdbe, "END");
! 4593: sqlite3ExplainPop(pVdbe);
! 4594: }
! 4595:
! 4596: /* End of the structure debug printing code
! 4597: *****************************************************************************/
! 4598: #endif /* defined(SQLITE_TEST) || defined(SQLITE_DEBUG) */
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