third_party/sqlite/src/ext/fts3/fts3_aux.c

   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
  15 #if !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3)
  16
  17 #include "fts3Int.h"
  18 #include <string.h>
  19 #include <assert.h>
  20
  21 typedef struct Fts3auxTable Fts3auxTable;
  22 typedef struct Fts3auxCursor Fts3auxCursor;
  23
  24 struct Fts3auxTable {
  25   sqlite3_vtab base;              /* Base class used by SQLite core */
  26   Fts3Table *pFts3Tab;
  27 };
  28
  29 struct Fts3auxCursor {
  30   sqlite3_vtab_cursor base;       /* Base class used by SQLite core */
  31   Fts3SegReaderCursor csr;        /* Must be right after "base" */
  32   Fts3SegFilter filter;
  33   char *zStop;
  34   int nStop;                      /* Byte-length of string zStop */
  35   int isEof;                      /* True if cursor is at EOF */
  36   sqlite3_int64 iRowid;           /* Current rowid */
  37
  38   int iCol;                       /* Current value of 'col' column */
  39   int nStat;                      /* Size of aStat[] array */
  40   struct Fts3auxColstats {
  41     sqlite3_int64 nDoc;           /* 'documents' values for current csr row */
  42     sqlite3_int64 nOcc;           /* 'occurrences' values for current csr row */
  43   } *aStat;
  44 };
  45
  46 /*
  47 ** Schema of the terms table.
  48 */
  49 #define FTS3_TERMS_SCHEMA "CREATE TABLE x(term, col, documents, occurrences)"
  50
  51 /*
  52 ** This function does all the work for both the xConnect and xCreate methods.
  53 ** These tables have no persistent representation of their own, so xConnect
  54 ** and xCreate are identical operations.
  55 */
  56 static int fts3auxConnectMethod(
  57   sqlite3 *db,                    /* Database connection */
  58   void *pUnused,                  /* Unused */
  59   int argc,                       /* Number of elements in argv array */
  60   const char * const *argv,       /* xCreate/xConnect argument array */
  61   sqlite3_vtab **ppVtab,          /* OUT: New sqlite3_vtab object */
  62   char **pzErr                    /* OUT: sqlite3_malloc'd error message */
  63 ){
  64   char const *zDb;                /* Name of database (e.g. "main") */
  65   char const *zFts3;              /* Name of fts3 table */
  66   int nDb;                        /* Result of strlen(zDb) */
  67   int nFts3;                      /* Result of strlen(zFts3) */
  68   int nByte;                      /* Bytes of space to allocate here */
  69   int rc;                         /* value returned by declare_vtab() */
  70   Fts3auxTable *p;                /* Virtual table object to return */
  71
  72   UNUSED_PARAMETER(pUnused);
  73
  74   /* The user should specify a single argument - the name of an fts3 table. */
  75   if( argc!=4 ){
  76     *pzErr = sqlite3_mprintf(
  77         "wrong number of arguments to fts4aux constructor"
  78     );
  79     return SQLITE_ERROR;
  80   }
  81
  82   zDb = argv[1];
  83   nDb = strlen(zDb);
  84   zFts3 = argv[3];
  85   nFts3 = strlen(zFts3);
  86
  87   rc = sqlite3_declare_vtab(db, FTS3_TERMS_SCHEMA);
  88   if( rc!=SQLITE_OK ) return rc;
  89
  90   nByte = sizeof(Fts3auxTable) + sizeof(Fts3Table) + nDb + nFts3 + 2;
  91   p = (Fts3auxTable *)sqlite3_malloc(nByte);
  92   if( !p ) return SQLITE_NOMEM;
  93   memset(p, 0, nByte);
  94
  95   p->pFts3Tab = (Fts3Table *)&p[1];
  96   p->pFts3Tab->zDb = (char *)&p->pFts3Tab[1];
  97   p->pFts3Tab->zName = &p->pFts3Tab->zDb[nDb+1];
  98   p->pFts3Tab->db = db;
  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
 346   assert( idxStr==0 );
 347   assert( idxNum==FTS4AUX_EQ_CONSTRAINT || idxNum==0
 348        || idxNum==FTS4AUX_LE_CONSTRAINT || idxNum==FTS4AUX_GE_CONSTRAINT
 349        || idxNum==(FTS4AUX_LE_CONSTRAINT|FTS4AUX_GE_CONSTRAINT)
 350   );
 351   isScan = (idxNum!=FTS4AUX_EQ_CONSTRAINT);
 352
 353   /* In case this cursor is being reused, close and zero it. */
 354   testcase(pCsr->filter.zTerm);
 355   sqlite3Fts3SegReaderFinish(&pCsr->csr);
 356   sqlite3_free((void *)pCsr->filter.zTerm);
 357   sqlite3_free(pCsr->aStat);
 358   memset(&pCsr->csr, 0, ((u8*)&pCsr[1]) - (u8*)&pCsr->csr);
 359
 360   pCsr->filter.flags = FTS3_SEGMENT_REQUIRE_POS|FTS3_SEGMENT_IGNORE_EMPTY;
 361   if( isScan ) pCsr->filter.flags |= FTS3_SEGMENT_SCAN;
 362
 363   if( idxNum&(FTS4AUX_EQ_CONSTRAINT|FTS4AUX_GE_CONSTRAINT) ){
 364     const unsigned char *zStr = sqlite3_value_text(apVal[0]);
 365     if( zStr ){
 366       pCsr->filter.zTerm = sqlite3_mprintf("%s", zStr);
 367       pCsr->filter.nTerm = sqlite3_value_bytes(apVal[0]);
 368       if( pCsr->filter.zTerm==0 ) return SQLITE_NOMEM;
 369     }
 370   }
 371   if( idxNum&FTS4AUX_LE_CONSTRAINT ){
 372     int iIdx = (idxNum&FTS4AUX_GE_CONSTRAINT) ? 1 : 0;
 373     pCsr->zStop = sqlite3_mprintf("%s", sqlite3_value_text(apVal[iIdx]));
 374     pCsr->nStop = sqlite3_value_bytes(apVal[iIdx]);
 375     if( pCsr->zStop==0 ) return SQLITE_NOMEM;
 376   }
 377
 378   rc = sqlite3Fts3SegReaderCursor(pFts3, FTS3_SEGCURSOR_ALL,
 379       pCsr->filter.zTerm, pCsr->filter.nTerm, 0, isScan, &pCsr->csr
 380   );
 381   if( rc==SQLITE_OK ){
 382     rc = sqlite3Fts3SegReaderStart(pFts3, &pCsr->csr, &pCsr->filter);
 383   }
 384
 385   if( rc==SQLITE_OK ) rc = fts3auxNextMethod(pCursor);
 386   return rc;
 387 }
 388
 389 /*
 390 ** xEof - Return true if the cursor is at EOF, or false otherwise.
 391 */
 392 static int fts3auxEofMethod(sqlite3_vtab_cursor *pCursor){
 393   Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor;
 394   return pCsr->isEof;
 395 }
 396
 397 /*
 398 ** xColumn - Return a column value.
 399 */
 400 static int fts3auxColumnMethod(
 401   sqlite3_vtab_cursor *pCursor,   /* Cursor to retrieve value from */
 402   sqlite3_context *pContext,      /* Context for sqlite3_result_xxx() calls */
 403   int iCol                        /* Index of column to read value from */
 404 ){
 405   Fts3auxCursor *p = (Fts3auxCursor *)pCursor;
 406
 407   assert( p->isEof==0 );
 408   if( iCol==0 ){        /* Column "term" */
 409     sqlite3_result_text(pContext, p->csr.zTerm, p->csr.nTerm, SQLITE_TRANSIENT);
 410   }else if( iCol==1 ){  /* Column "col" */
 411     if( p->iCol ){
 412       sqlite3_result_int(pContext, p->iCol-1);
 413     }else{
 414       sqlite3_result_text(pContext, "*", -1, SQLITE_STATIC);
 415     }
 416   }else if( iCol==2 ){  /* Column "documents" */
 417     sqlite3_result_int64(pContext, p->aStat[p->iCol].nDoc);
 418   }else{                /* Column "occurrences" */
 419     sqlite3_result_int64(pContext, p->aStat[p->iCol].nOcc);
 420   }
 421
 422   return SQLITE_OK;
 423 }
 424
 425 /*
 426 ** xRowid - Return the current rowid for the cursor.
 427 */
 428 static int fts3auxRowidMethod(
 429   sqlite3_vtab_cursor *pCursor,   /* Cursor to retrieve value from */
 430   sqlite_int64 *pRowid            /* OUT: Rowid value */
 431 ){
 432   Fts3auxCursor *pCsr = (Fts3auxCursor *)pCursor;
 433   *pRowid = pCsr->iRowid;
 434   return SQLITE_OK;
 435 }
 436
 437 /*
 438 ** Register the fts3aux module with database connection db. Return SQLITE_OK
 439 ** if successful or an error code if sqlite3_create_module() fails.
 440 */
 441 int sqlite3Fts3InitAux(sqlite3 *db){
 442   static const sqlite3_module fts3aux_module = {
 443      0,                           /* iVersion      */
 444      fts3auxConnectMethod,        /* xCreate       */
 445      fts3auxConnectMethod,        /* xConnect      */
 446      fts3auxBestIndexMethod,      /* xBestIndex    */
 447      fts3auxDisconnectMethod,     /* xDisconnect   */
 448      fts3auxDisconnectMethod,     /* xDestroy      */
 449      fts3auxOpenMethod,           /* xOpen         */
 450      fts3auxCloseMethod,          /* xClose        */
 451      fts3auxFilterMethod,         /* xFilter       */
 452      fts3auxNextMethod,           /* xNext         */
 453      fts3auxEofMethod,            /* xEof          */
 454      fts3auxColumnMethod,         /* xColumn       */
 455      fts3auxRowidMethod,          /* xRowid        */
 456      0,                           /* xUpdate       */
 457      0,                           /* xBegin        */
 458      0,                           /* xSync         */
 459      0,                           /* xCommit       */
 460      0,                           /* xRollback     */
 461      0,                           /* xFindFunction */
 462      0                            /* xRename       */
 463   };
 464   int rc;                         /* Return code */
 465
 466   rc = sqlite3_create_module(db, "fts4aux", &fts3aux_module, 0);
 467   return rc;
 468 }
 469
 470 #endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_FTS3) */