Annotation of embedaddon/sqlite3/ext/fts3/fts3_aux.c, revision 1.1.1.1
1.1 misho 1: /*
2: ** 2011 Jan 27
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: **
13: */
14: #include "fts3Int.h"
15: #if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
16:
17: #include <string.h>
18: #include <assert.h>
19:
20: typedef struct Fts3auxTable Fts3auxTable;
21: typedef struct Fts3auxCursor Fts3auxCursor;
22:
23: struct Fts3auxTable {
24: sqlite3_vtab base; /* Base class used by SQLite core */
25: Fts3Table *pFts3Tab;
26: };
27:
28: struct Fts3auxCursor {
29: sqlite3_vtab_cursor base; /* Base class used by SQLite core */
30: Fts3MultiSegReader csr; /* Must be right after "base" */
31: Fts3SegFilter filter;
32: char *zStop;
33: int nStop; /* Byte-length of string zStop */
34: int isEof; /* True if cursor is at EOF */
35: sqlite3_int64 iRowid; /* Current rowid */
36:
37: int iCol; /* Current value of 'col' column */
38: int nStat; /* Size of aStat[] array */
39: struct Fts3auxColstats {
40: sqlite3_int64 nDoc; /* 'documents' values for current csr row */
41: sqlite3_int64 nOcc; /* 'occurrences' values for current csr row */
42: } *aStat;
43: };
44:
45: /*
46: ** Schema of the terms table.
47: */
48: #define FTS3_TERMS_SCHEMA "CREATE TABLE x(term, col, documents, occurrences)"
49:
50: /*
51: ** This function does all the work for both the xConnect and xCreate methods.
52: ** These tables have no persistent representation of their own, so xConnect
53: ** and xCreate are identical operations.
54: */
55: static int fts3auxConnectMethod(
56: sqlite3 *db, /* Database connection */
57: void *pUnused, /* Unused */
58: int argc, /* Number of elements in argv array */
59: const char * const *argv, /* xCreate/xConnect argument array */
60: sqlite3_vtab **ppVtab, /* OUT: New sqlite3_vtab object */
61: char **pzErr /* OUT: sqlite3_malloc'd error message */
62: ){
63: char const *zDb; /* Name of database (e.g. "main") */
64: char const *zFts3; /* Name of fts3 table */
65: int nDb; /* Result of strlen(zDb) */
66: int nFts3; /* Result of strlen(zFts3) */
67: int nByte; /* Bytes of space to allocate here */
68: int rc; /* value returned by declare_vtab() */
69: Fts3auxTable *p; /* Virtual table object to return */
70:
71: UNUSED_PARAMETER(pUnused);
72:
73: /* The user should specify a single argument - the name of an fts3 table. */
74: if( argc!=4 ){
75: *pzErr = sqlite3_mprintf(
76: "wrong number of arguments to fts4aux constructor"
77: );
78: return SQLITE_ERROR;
79: }
80:
81: zDb = argv[1];
82: nDb = strlen(zDb);
83: zFts3 = argv[3];
84: nFts3 = strlen(zFts3);
85:
86: rc = sqlite3_declare_vtab(db, FTS3_TERMS_SCHEMA);
87: if( rc!=SQLITE_OK ) return rc;
88:
89: nByte = sizeof(Fts3auxTable) + sizeof(Fts3Table) + nDb + nFts3 + 2;
90: p = (Fts3auxTable *)sqlite3_malloc(nByte);
91: if( !p ) return SQLITE_NOMEM;
92: memset(p, 0, nByte);
93:
94: p->pFts3Tab = (Fts3Table *)&p[1];
95: p->pFts3Tab->zDb = (char *)&p->pFts3Tab[1];
96: p->pFts3Tab->zName = &p->pFts3Tab->zDb[nDb+1];
97: p->pFts3Tab->db = db;
98: p->pFts3Tab->nIndex = 1;
99:
100: memcpy((char *)p->pFts3Tab->zDb, zDb, nDb);
101: memcpy((char *)p->pFts3Tab->zName, zFts3, nFts3);
102: sqlite3Fts3Dequote((char *)p->pFts3Tab->zName);
103:
104: *ppVtab = (sqlite3_vtab *)p;
105: return SQLITE_OK;
106: }
107:
108: /*
109: ** This function does the work for both the xDisconnect and xDestroy methods.
110: ** These tables have no persistent representation of their own, so xDisconnect
111: ** and xDestroy are identical operations.
112: */
113: static int fts3auxDisconnectMethod(sqlite3_vtab *pVtab){
114: Fts3auxTable *p = (Fts3auxTable *)pVtab;
115: Fts3Table *pFts3 = p->pFts3Tab;
116: int i;
117:
118: /* Free any prepared statements held */
119: for(i=0; i<SizeofArray(pFts3->aStmt); i++){
120: sqlite3_finalize(pFts3->aStmt[i]);
121: }
122: sqlite3_free(pFts3->zSegmentsTbl);
123: sqlite3_free(p);
124: return SQLITE_OK;
125: }
126:
127: #define FTS4AUX_EQ_CONSTRAINT 1
128: #define FTS4AUX_GE_CONSTRAINT 2
129: #define FTS4AUX_LE_CONSTRAINT 4
130:
131: /*
132: ** xBestIndex - Analyze a WHERE and ORDER BY clause.
133: */
134: static int fts3auxBestIndexMethod(
135: sqlite3_vtab *pVTab,
136: sqlite3_index_info *pInfo
137: ){
138: int i;
139: int iEq = -1;
140: int iGe = -1;
141: int iLe = -1;
142:
143: UNUSED_PARAMETER(pVTab);
144:
145: /* This vtab delivers always results in "ORDER BY term ASC" order. */
146: if( pInfo->nOrderBy==1
147: && pInfo->aOrderBy[0].iColumn==0
148: && pInfo->aOrderBy[0].desc==0
149: ){
150: pInfo->orderByConsumed = 1;
151: }
152:
153: /* Search for equality and range constraints on the "term" column. */
154: for(i=0; i<pInfo->nConstraint; i++){
155: if( pInfo->aConstraint[i].usable && pInfo->aConstraint[i].iColumn==0 ){
156: int op = pInfo->aConstraint[i].op;
157: if( op==SQLITE_INDEX_CONSTRAINT_EQ ) iEq = i;
158: if( op==SQLITE_INDEX_CONSTRAINT_LT ) iLe = i;
159: if( op==SQLITE_INDEX_CONSTRAINT_LE ) iLe = i;
160: if( op==SQLITE_INDEX_CONSTRAINT_GT ) iGe = i;
161: if( op==SQLITE_INDEX_CONSTRAINT_GE ) iGe = i;
162: }
163: }
164:
165: if( iEq>=0 ){
166: pInfo->idxNum = FTS4AUX_EQ_CONSTRAINT;
167: pInfo->aConstraintUsage[iEq].argvIndex = 1;
168: pInfo->estimatedCost = 5;
169: }else{
170: pInfo->idxNum = 0;
171: pInfo->estimatedCost = 20000;
172: if( iGe>=0 ){
173: pInfo->idxNum += FTS4AUX_GE_CONSTRAINT;
174: pInfo->aConstraintUsage[iGe].argvIndex = 1;
175: pInfo->estimatedCost /= 2;
176: }
177: if( iLe>=0 ){
178: pInfo->idxNum += FTS4AUX_LE_CONSTRAINT;
179: pInfo->aConstraintUsage[iLe].argvIndex = 1 + (iGe>=0);
180: pInfo->estimatedCost /= 2;
181: }
182: }
183:
184: return SQLITE_OK;
185: }
186:
187: /*
188: ** xOpen - Open a cursor.
189: */
190: static int fts3auxOpenMethod(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCsr){
191: Fts3auxCursor *pCsr; /* Pointer to cursor object to return */
192:
193: UNUSED_PARAMETER(pVTab);
194:
195: pCsr = (Fts3auxCursor *)sqlite3_malloc(sizeof(Fts3auxCursor));
196: if( !pCsr ) return SQLITE_NOMEM;
197: memset(pCsr, 0, sizeof(Fts3auxCursor));
198:
199: *ppCsr = (sqlite3_vtab_cursor *)pCsr;
200: return SQLITE_OK;
201: }
202:
203: /*
204: ** xClose - Close a cursor.
205: */
206: static int fts3auxCloseMethod(sqlite3_vtab_cursor *pCursor){
207: Fts3Table *pFts3 = ((Fts3auxTable *)pCursor->pVtab)->pFts3Tab;
208: Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor;
209:
210: sqlite3Fts3SegmentsClose(pFts3);
211: sqlite3Fts3SegReaderFinish(&pCsr->csr);
212: sqlite3_free((void *)pCsr->filter.zTerm);
213: sqlite3_free(pCsr->zStop);
214: sqlite3_free(pCsr->aStat);
215: sqlite3_free(pCsr);
216: return SQLITE_OK;
217: }
218:
219: static int fts3auxGrowStatArray(Fts3auxCursor *pCsr, int nSize){
220: if( nSize>pCsr->nStat ){
221: struct Fts3auxColstats *aNew;
222: aNew = (struct Fts3auxColstats *)sqlite3_realloc(pCsr->aStat,
223: sizeof(struct Fts3auxColstats) * nSize
224: );
225: if( aNew==0 ) return SQLITE_NOMEM;
226: memset(&aNew[pCsr->nStat], 0,
227: sizeof(struct Fts3auxColstats) * (nSize - pCsr->nStat)
228: );
229: pCsr->aStat = aNew;
230: pCsr->nStat = nSize;
231: }
232: return SQLITE_OK;
233: }
234:
235: /*
236: ** xNext - Advance the cursor to the next row, if any.
237: */
238: static int fts3auxNextMethod(sqlite3_vtab_cursor *pCursor){
239: Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor;
240: Fts3Table *pFts3 = ((Fts3auxTable *)pCursor->pVtab)->pFts3Tab;
241: int rc;
242:
243: /* Increment our pretend rowid value. */
244: pCsr->iRowid++;
245:
246: for(pCsr->iCol++; pCsr->iCol<pCsr->nStat; pCsr->iCol++){
247: if( pCsr->aStat[pCsr->iCol].nDoc>0 ) return SQLITE_OK;
248: }
249:
250: rc = sqlite3Fts3SegReaderStep(pFts3, &pCsr->csr);
251: if( rc==SQLITE_ROW ){
252: int i = 0;
253: int nDoclist = pCsr->csr.nDoclist;
254: char *aDoclist = pCsr->csr.aDoclist;
255: int iCol;
256:
257: int eState = 0;
258:
259: if( pCsr->zStop ){
260: int n = (pCsr->nStop<pCsr->csr.nTerm) ? pCsr->nStop : pCsr->csr.nTerm;
261: int mc = memcmp(pCsr->zStop, pCsr->csr.zTerm, n);
262: if( mc<0 || (mc==0 && pCsr->csr.nTerm>pCsr->nStop) ){
263: pCsr->isEof = 1;
264: return SQLITE_OK;
265: }
266: }
267:
268: if( fts3auxGrowStatArray(pCsr, 2) ) return SQLITE_NOMEM;
269: memset(pCsr->aStat, 0, sizeof(struct Fts3auxColstats) * pCsr->nStat);
270: iCol = 0;
271:
272: while( i<nDoclist ){
273: sqlite3_int64 v = 0;
274:
275: i += sqlite3Fts3GetVarint(&aDoclist[i], &v);
276: switch( eState ){
277: /* State 0. In this state the integer just read was a docid. */
278: case 0:
279: pCsr->aStat[0].nDoc++;
280: eState = 1;
281: iCol = 0;
282: break;
283:
284: /* State 1. In this state we are expecting either a 1, indicating
285: ** that the following integer will be a column number, or the
286: ** start of a position list for column 0.
287: **
288: ** The only difference between state 1 and state 2 is that if the
289: ** integer encountered in state 1 is not 0 or 1, then we need to
290: ** increment the column 0 "nDoc" count for this term.
291: */
292: case 1:
293: assert( iCol==0 );
294: if( v>1 ){
295: pCsr->aStat[1].nDoc++;
296: }
297: eState = 2;
298: /* fall through */
299:
300: case 2:
301: if( v==0 ){ /* 0x00. Next integer will be a docid. */
302: eState = 0;
303: }else if( v==1 ){ /* 0x01. Next integer will be a column number. */
304: eState = 3;
305: }else{ /* 2 or greater. A position. */
306: pCsr->aStat[iCol+1].nOcc++;
307: pCsr->aStat[0].nOcc++;
308: }
309: break;
310:
311: /* State 3. The integer just read is a column number. */
312: default: assert( eState==3 );
313: iCol = (int)v;
314: if( fts3auxGrowStatArray(pCsr, iCol+2) ) return SQLITE_NOMEM;
315: pCsr->aStat[iCol+1].nDoc++;
316: eState = 2;
317: break;
318: }
319: }
320:
321: pCsr->iCol = 0;
322: rc = SQLITE_OK;
323: }else{
324: pCsr->isEof = 1;
325: }
326: return rc;
327: }
328:
329: /*
330: ** xFilter - Initialize a cursor to point at the start of its data.
331: */
332: static int fts3auxFilterMethod(
333: sqlite3_vtab_cursor *pCursor, /* The cursor used for this query */
334: int idxNum, /* Strategy index */
335: const char *idxStr, /* Unused */
336: int nVal, /* Number of elements in apVal */
337: sqlite3_value **apVal /* Arguments for the indexing scheme */
338: ){
339: Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor;
340: Fts3Table *pFts3 = ((Fts3auxTable *)pCursor->pVtab)->pFts3Tab;
341: int rc;
342: int isScan;
343:
344: UNUSED_PARAMETER(nVal);
345: UNUSED_PARAMETER(idxStr);
346:
347: assert( idxStr==0 );
348: assert( idxNum==FTS4AUX_EQ_CONSTRAINT || idxNum==0
349: || idxNum==FTS4AUX_LE_CONSTRAINT || idxNum==FTS4AUX_GE_CONSTRAINT
350: || idxNum==(FTS4AUX_LE_CONSTRAINT|FTS4AUX_GE_CONSTRAINT)
351: );
352: isScan = (idxNum!=FTS4AUX_EQ_CONSTRAINT);
353:
354: /* In case this cursor is being reused, close and zero it. */
355: testcase(pCsr->filter.zTerm);
356: sqlite3Fts3SegReaderFinish(&pCsr->csr);
357: sqlite3_free((void *)pCsr->filter.zTerm);
358: sqlite3_free(pCsr->aStat);
359: memset(&pCsr->csr, 0, ((u8*)&pCsr[1]) - (u8*)&pCsr->csr);
360:
361: pCsr->filter.flags = FTS3_SEGMENT_REQUIRE_POS|FTS3_SEGMENT_IGNORE_EMPTY;
362: if( isScan ) pCsr->filter.flags |= FTS3_SEGMENT_SCAN;
363:
364: if( idxNum&(FTS4AUX_EQ_CONSTRAINT|FTS4AUX_GE_CONSTRAINT) ){
365: const unsigned char *zStr = sqlite3_value_text(apVal[0]);
366: if( zStr ){
367: pCsr->filter.zTerm = sqlite3_mprintf("%s", zStr);
368: pCsr->filter.nTerm = sqlite3_value_bytes(apVal[0]);
369: if( pCsr->filter.zTerm==0 ) return SQLITE_NOMEM;
370: }
371: }
372: if( idxNum&FTS4AUX_LE_CONSTRAINT ){
373: int iIdx = (idxNum&FTS4AUX_GE_CONSTRAINT) ? 1 : 0;
374: pCsr->zStop = sqlite3_mprintf("%s", sqlite3_value_text(apVal[iIdx]));
375: pCsr->nStop = sqlite3_value_bytes(apVal[iIdx]);
376: if( pCsr->zStop==0 ) return SQLITE_NOMEM;
377: }
378:
379: rc = sqlite3Fts3SegReaderCursor(pFts3, 0, FTS3_SEGCURSOR_ALL,
380: pCsr->filter.zTerm, pCsr->filter.nTerm, 0, isScan, &pCsr->csr
381: );
382: if( rc==SQLITE_OK ){
383: rc = sqlite3Fts3SegReaderStart(pFts3, &pCsr->csr, &pCsr->filter);
384: }
385:
386: if( rc==SQLITE_OK ) rc = fts3auxNextMethod(pCursor);
387: return rc;
388: }
389:
390: /*
391: ** xEof - Return true if the cursor is at EOF, or false otherwise.
392: */
393: static int fts3auxEofMethod(sqlite3_vtab_cursor *pCursor){
394: Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor;
395: return pCsr->isEof;
396: }
397:
398: /*
399: ** xColumn - Return a column value.
400: */
401: static int fts3auxColumnMethod(
402: sqlite3_vtab_cursor *pCursor, /* Cursor to retrieve value from */
403: sqlite3_context *pContext, /* Context for sqlite3_result_xxx() calls */
404: int iCol /* Index of column to read value from */
405: ){
406: Fts3auxCursor *p = (Fts3auxCursor *)pCursor;
407:
408: assert( p->isEof==0 );
409: if( iCol==0 ){ /* Column "term" */
410: sqlite3_result_text(pContext, p->csr.zTerm, p->csr.nTerm, SQLITE_TRANSIENT);
411: }else if( iCol==1 ){ /* Column "col" */
412: if( p->iCol ){
413: sqlite3_result_int(pContext, p->iCol-1);
414: }else{
415: sqlite3_result_text(pContext, "*", -1, SQLITE_STATIC);
416: }
417: }else if( iCol==2 ){ /* Column "documents" */
418: sqlite3_result_int64(pContext, p->aStat[p->iCol].nDoc);
419: }else{ /* Column "occurrences" */
420: sqlite3_result_int64(pContext, p->aStat[p->iCol].nOcc);
421: }
422:
423: return SQLITE_OK;
424: }
425:
426: /*
427: ** xRowid - Return the current rowid for the cursor.
428: */
429: static int fts3auxRowidMethod(
430: sqlite3_vtab_cursor *pCursor, /* Cursor to retrieve value from */
431: sqlite_int64 *pRowid /* OUT: Rowid value */
432: ){
433: Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor;
434: *pRowid = pCsr->iRowid;
435: return SQLITE_OK;
436: }
437:
438: /*
439: ** Register the fts3aux module with database connection db. Return SQLITE_OK
440: ** if successful or an error code if sqlite3_create_module() fails.
441: */
442: int sqlite3Fts3InitAux(sqlite3 *db){
443: static const sqlite3_module fts3aux_module = {
444: 0, /* iVersion */
445: fts3auxConnectMethod, /* xCreate */
446: fts3auxConnectMethod, /* xConnect */
447: fts3auxBestIndexMethod, /* xBestIndex */
448: fts3auxDisconnectMethod, /* xDisconnect */
449: fts3auxDisconnectMethod, /* xDestroy */
450: fts3auxOpenMethod, /* xOpen */
451: fts3auxCloseMethod, /* xClose */
452: fts3auxFilterMethod, /* xFilter */
453: fts3auxNextMethod, /* xNext */
454: fts3auxEofMethod, /* xEof */
455: fts3auxColumnMethod, /* xColumn */
456: fts3auxRowidMethod, /* xRowid */
457: 0, /* xUpdate */
458: 0, /* xBegin */
459: 0, /* xSync */
460: 0, /* xCommit */
461: 0, /* xRollback */
462: 0, /* xFindFunction */
463: 0, /* xRename */
464: 0, /* xSavepoint */
465: 0, /* xRelease */
466: 0 /* xRollbackTo */
467: };
468: int rc; /* Return code */
469:
470: rc = sqlite3_create_module(db, "fts4aux", &fts3aux_module, 0);
471: return rc;
472: }
473:
474: #endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */
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