src/delete.c

   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 ** in order to generate code for DELETE FROM statements.
  14 */
  15 #include "sqliteInt.h"
  16
  17 /*
  18 ** While a SrcList can in general represent multiple tables and subqueries
  19 ** (as in the FROM clause of a SELECT statement) in this case it contains
  20 ** the name of a single table, as one might find in an INSERT, DELETE,
  21 ** or UPDATE statement.  Look up that table in the symbol table and
  22 ** return a pointer.  Set an error message and return NULL if the table
  23 ** name is not found or if any other error occurs.
  24 **
  25 ** The following fields are initialized appropriate in pSrc:
  26 **
  27 **    pSrc->a[0].pTab       Pointer to the Table object
  28 **    pSrc->a[0].pIndex     Pointer to the INDEXED BY index, if there is one
  29 **
  30 */
  31 Table *sqlite3SrcListLookup(Parse *pParse, SrcList *pSrc){
  32   SrcItem *pItem = pSrc->a;
  33   Table *pTab;
  34   assert( pItem && pSrc->nSrc>=1 );
  35   pTab = sqlite3LocateTableItem(pParse, 0, pItem);
  36   sqlite3DeleteTable(pParse->db, pItem->pTab);
  37   pItem->pTab = pTab;
  38   if( pTab ){
  39     pTab->nTabRef++;
  40     if( pItem->fg.isIndexedBy && sqlite3IndexedByLookup(pParse, pItem) ){
  41       pTab = 0;
  42     }
  43   }
  44   return pTab;
  45 }
  46
  47 /* Generate byte-code that will report the number of rows modified
  48 ** by a DELETE, INSERT, or UPDATE statement.
  49 */
  50 void sqlite3CodeChangeCount(Vdbe *v, int regCounter, const char *zColName){
  51   sqlite3VdbeAddOp0(v, OP_FkCheck);
  52   sqlite3VdbeAddOp2(v, OP_ResultRow, regCounter, 1);
  53   sqlite3VdbeSetNumCols(v, 1);
  54   sqlite3VdbeSetColName(v, 0, COLNAME_NAME, zColName, SQLITE_STATIC);
  55 }
  56
  57 /* Return true if table pTab is read-only.
  58 **
  59 ** A table is read-only if any of the following are true:
  60 **
  61 **   1) It is a virtual table and no implementation of the xUpdate method
  62 **      has been provided
  63 **
  64 **   2) A trigger is currently being coded and the table is a virtual table
  65 **      that is SQLITE_VTAB_DIRECTONLY or if PRAGMA trusted_schema=OFF and
  66 **      the table is not SQLITE_VTAB_INNOCUOUS.
  67 **
  68 **   3) It is a system table (i.e. sqlite_schema), this call is not
  69 **      part of a nested parse and writable_schema pragma has not
  70 **      been specified
  71 **
  72 **   4) The table is a shadow table, the database connection is in
  73 **      defensive mode, and the current sqlite3_prepare()
  74 **      is for a top-level SQL statement.
  75 */
  76 static int vtabIsReadOnly(Parse *pParse, Table *pTab){
  77   if( sqlite3GetVTable(pParse->db, pTab)->pMod->pModule->xUpdate==0 ){
  78     return 1;
  79   }
  80
  81   /* Within triggers:
  82   **   *  Do not allow DELETE, INSERT, or UPDATE of SQLITE_VTAB_DIRECTONLY
  83   **      virtual tables
  84   **   *  Only allow DELETE, INSERT, or UPDATE of non-SQLITE_VTAB_INNOCUOUS
  85   **      virtual tables if PRAGMA trusted_schema=ON.
  86   */
  87   if( pParse->pToplevel!=0
  88    && pTab->u.vtab.p->eVtabRisk >
  89            ((pParse->db->flags & SQLITE_TrustedSchema)!=0)
  90   ){
  91     sqlite3ErrorMsg(pParse, "unsafe use of virtual table \"%s\"",
  92       pTab->zName);
  93   }
  94   return 0;
  95 }
  96 static int tabIsReadOnly(Parse *pParse, Table *pTab){
  97   sqlite3 *db;
  98   if( IsVirtual(pTab) ){
  99     return vtabIsReadOnly(pParse, pTab);
 100   }
 101   if( (pTab->tabFlags & (TF_Readonly|TF_Shadow))==0 ) return 0;
 102   db = pParse->db;
 103   if( (pTab->tabFlags & TF_Readonly)!=0 ){
 104     return sqlite3WritableSchema(db)==0 && pParse->nested==0;
 105   }
 106   assert( pTab->tabFlags & TF_Shadow );
 107   return sqlite3ReadOnlyShadowTables(db);
 108 }
 109
 110 /*
 111 ** Check to make sure the given table is writable.
 112 **
 113 ** If pTab is not writable  ->  generate an error message and return 1.
 114 ** If pTab is writable but other errors have occurred -> return 1.
 115 ** If pTab is writable and no prior errors -> return 0;
 116 */
 117 int sqlite3IsReadOnly(Parse *pParse, Table *pTab, Trigger *pTrigger){
 118   if( tabIsReadOnly(pParse, pTab) ){
 119     sqlite3ErrorMsg(pParse, "table %s may not be modified", pTab->zName);
 120     return 1;
 121   }
 122 #ifndef SQLITE_OMIT_VIEW
 123   if( IsView(pTab)
 124    && (pTrigger==0 || (pTrigger->bReturning && pTrigger->pNext==0))
 125   ){
 126     sqlite3ErrorMsg(pParse,"cannot modify %s because it is a view",pTab->zName);
 127     return 1;
 128   }
 129 #endif
 130   return 0;
 131 }
 132
 133
 134 #if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
 135 /*
 136 ** Evaluate a view and store its result in an ephemeral table.  The
 137 ** pWhere argument is an optional WHERE clause that restricts the
 138 ** set of rows in the view that are to be added to the ephemeral table.
 139 */
 140 void sqlite3MaterializeView(
 141   Parse *pParse,       /* Parsing context */
 142   Table *pView,        /* View definition */
 143   Expr *pWhere,        /* Optional WHERE clause to be added */
 144   ExprList *pOrderBy,  /* Optional ORDER BY clause */
 145   Expr *pLimit,        /* Optional LIMIT clause */
 146   int iCur             /* Cursor number for ephemeral table */
 147 ){
 148   SelectDest dest;
 149   Select *pSel;
 150   SrcList *pFrom;
 151   sqlite3 *db = pParse->db;
 152   int iDb = sqlite3SchemaToIndex(db, pView->pSchema);
 153   pWhere = sqlite3ExprDup(db, pWhere, 0);
 154   pFrom = sqlite3SrcListAppend(pParse, 0, 0, 0);
 155   if( pFrom ){
 156     assert( pFrom->nSrc==1 );
 157     pFrom->a[0].zName = sqlite3DbStrDup(db, pView->zName);
 158     pFrom->a[0].zDatabase = sqlite3DbStrDup(db, db->aDb[iDb].zDbSName);
 159     assert( pFrom->a[0].fg.isUsing==0 );
 160     assert( pFrom->a[0].u3.pOn==0 );
 161   }
 162   pSel = sqlite3SelectNew(pParse, 0, pFrom, pWhere, 0, 0, pOrderBy,
 163                           SF_IncludeHidden, pLimit);
 164   sqlite3SelectDestInit(&dest, SRT_EphemTab, iCur);
 165   sqlite3Select(pParse, pSel, &dest);
 166   sqlite3SelectDelete(db, pSel);
 167 }
 168 #endif /* !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER) */
 169
 170 #if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
 171 /*
 172 ** Generate an expression tree to implement the WHERE, ORDER BY,
 173 ** and LIMIT/OFFSET portion of DELETE and UPDATE statements.
 174 **
 175 **     DELETE FROM table_wxyz WHERE a<5 ORDER BY a LIMIT 1;
 176 **                            \__________________________/
 177 **                               pLimitWhere (pInClause)
 178 */
 179 Expr *sqlite3LimitWhere(
 180   Parse *pParse,               /* The parser context */
 181   SrcList *pSrc,               /* the FROM clause -- which tables to scan */
 182   Expr *pWhere,                /* The WHERE clause.  May be null */
 183   ExprList *pOrderBy,          /* The ORDER BY clause.  May be null */
 184   Expr *pLimit,                /* The LIMIT clause.  May be null */
 185   char *zStmtType              /* Either DELETE or UPDATE.  For err msgs. */
 186 ){
 187   sqlite3 *db = pParse->db;
 188   Expr *pLhs = NULL;           /* LHS of IN(SELECT...) operator */
 189   Expr *pInClause = NULL;      /* WHERE rowid IN ( select ) */
 190   ExprList *pEList = NULL;     /* Expression list contaning only pSelectRowid */
 191   SrcList *pSelectSrc = NULL;  /* SELECT rowid FROM x ... (dup of pSrc) */
 192   Select *pSelect = NULL;      /* Complete SELECT tree */
 193   Table *pTab;
 194
 195   /* Check that there isn't an ORDER BY without a LIMIT clause.
 196   */
 197   if( pOrderBy && pLimit==0 ) {
 198     sqlite3ErrorMsg(pParse, "ORDER BY without LIMIT on %s", zStmtType);
 199     sqlite3ExprDelete(pParse->db, pWhere);
 200     sqlite3ExprListDelete(pParse->db, pOrderBy);
 201     return 0;
 202   }
 203
 204   /* We only need to generate a select expression if there
 205   ** is a limit/offset term to enforce.
 206   */
 207   if( pLimit == 0 ) {
 208     return pWhere;
 209   }
 210
 211   /* Generate a select expression tree to enforce the limit/offset
 212   ** term for the DELETE or UPDATE statement.  For example:
 213   **   DELETE FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
 214   ** becomes:
 215   **   DELETE FROM table_a WHERE rowid IN (
 216   **     SELECT rowid FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
 217   **   );
 218   */
 219
 220   pTab = pSrc->a[0].pTab;
 221   if( HasRowid(pTab) ){
 222     pLhs = sqlite3PExpr(pParse, TK_ROW, 0, 0);
 223     pEList = sqlite3ExprListAppend(
 224         pParse, 0, sqlite3PExpr(pParse, TK_ROW, 0, 0)
 225     );
 226   }else{
 227     Index *pPk = sqlite3PrimaryKeyIndex(pTab);
 228     if( pPk->nKeyCol==1 ){
 229       const char *zName = pTab->aCol[pPk->aiColumn[0]].zCnName;
 230       pLhs = sqlite3Expr(db, TK_ID, zName);
 231       pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db, TK_ID, zName));
 232     }else{
 233       int i;
 234       for(i=0; i<pPk->nKeyCol; i++){
 235         Expr *p = sqlite3Expr(db, TK_ID, pTab->aCol[pPk->aiColumn[i]].zCnName);
 236         pEList = sqlite3ExprListAppend(pParse, pEList, p);
 237       }
 238       pLhs = sqlite3PExpr(pParse, TK_VECTOR, 0, 0);
 239       if( pLhs ){
 240         pLhs->x.pList = sqlite3ExprListDup(db, pEList, 0);
 241       }
 242     }
 243   }
 244
 245   /* duplicate the FROM clause as it is needed by both the DELETE/UPDATE tree
 246   ** and the SELECT subtree. */
 247   pSrc->a[0].pTab = 0;
 248   pSelectSrc = sqlite3SrcListDup(db, pSrc, 0);
 249   pSrc->a[0].pTab = pTab;
 250   if( pSrc->a[0].fg.isIndexedBy ){
 251     assert( pSrc->a[0].fg.isCte==0 );
 252     pSrc->a[0].u2.pIBIndex = 0;
 253     pSrc->a[0].fg.isIndexedBy = 0;
 254     sqlite3DbFree(db, pSrc->a[0].u1.zIndexedBy);
 255   }else if( pSrc->a[0].fg.isCte ){
 256     pSrc->a[0].u2.pCteUse->nUse++;
 257   }
 258
 259   /* generate the SELECT expression tree. */
 260   pSelect = sqlite3SelectNew(pParse, pEList, pSelectSrc, pWhere, 0 ,0,
 261       pOrderBy,0,pLimit
 262   );
 263
 264   /* now generate the new WHERE rowid IN clause for the DELETE/UDPATE */
 265   pInClause = sqlite3PExpr(pParse, TK_IN, pLhs, 0);
 266   sqlite3PExprAddSelect(pParse, pInClause, pSelect);
 267   return pInClause;
 268 }
 269 #endif /* defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) */
 270        /*      && !defined(SQLITE_OMIT_SUBQUERY) */
 271
 272 /*
 273 ** Generate code for a DELETE FROM statement.
 274 **
 275 **     DELETE FROM table_wxyz WHERE a<5 AND b NOT NULL;
 276 **                 \________/       \________________/
 277 **                  pTabList              pWhere
 278 */
 279 void sqlite3DeleteFrom(
 280   Parse *pParse,         /* The parser context */
 281   SrcList *pTabList,     /* The table from which we should delete things */
 282   Expr *pWhere,          /* The WHERE clause.  May be null */
 283   ExprList *pOrderBy,    /* ORDER BY clause. May be null */
 284   Expr *pLimit           /* LIMIT clause. May be null */
 285 ){
 286   Vdbe *v;               /* The virtual database engine */
 287   Table *pTab;           /* The table from which records will be deleted */
 288   int i;                 /* Loop counter */
 289   WhereInfo *pWInfo;     /* Information about the WHERE clause */
 290   Index *pIdx;           /* For looping over indices of the table */
 291   int iTabCur;           /* Cursor number for the table */
 292   int iDataCur = 0;      /* VDBE cursor for the canonical data source */
 293   int iIdxCur = 0;       /* Cursor number of the first index */
 294   int nIdx;              /* Number of indices */
 295   sqlite3 *db;           /* Main database structure */
 296   AuthContext sContext;  /* Authorization context */
 297   NameContext sNC;       /* Name context to resolve expressions in */
 298   int iDb;               /* Database number */
 299   int memCnt = 0;        /* Memory cell used for change counting */
 300   int rcauth;            /* Value returned by authorization callback */
 301   int eOnePass;          /* ONEPASS_OFF or _SINGLE or _MULTI */
 302   int aiCurOnePass[2];   /* The write cursors opened by WHERE_ONEPASS */
 303   u8 *aToOpen = 0;       /* Open cursor iTabCur+j if aToOpen[j] is true */
 304   Index *pPk;            /* The PRIMARY KEY index on the table */
 305   int iPk = 0;           /* First of nPk registers holding PRIMARY KEY value */
 306   i16 nPk = 1;           /* Number of columns in the PRIMARY KEY */
 307   int iKey;              /* Memory cell holding key of row to be deleted */
 308   i16 nKey;              /* Number of memory cells in the row key */
 309   int iEphCur = 0;       /* Ephemeral table holding all primary key values */
 310   int iRowSet = 0;       /* Register for rowset of rows to delete */
 311   int addrBypass = 0;    /* Address of jump over the delete logic */
 312   int addrLoop = 0;      /* Top of the delete loop */
 313   int addrEphOpen = 0;   /* Instruction to open the Ephemeral table */
 314   int bComplex;          /* True if there are triggers or FKs or
 315                          ** subqueries in the WHERE clause */
 316
 317 #ifndef SQLITE_OMIT_TRIGGER
 318   int isView;                  /* True if attempting to delete from a view */
 319   Trigger *pTrigger;           /* List of table triggers, if required */
 320 #endif
 321
 322   memset(&sContext, 0, sizeof(sContext));
 323   db = pParse->db;
 324   assert( db->pParse==pParse );
 325   if( pParse->nErr ){
 326     goto delete_from_cleanup;
 327   }
 328   assert( db->mallocFailed==0 );
 329   assert( pTabList->nSrc==1 );
 330
 331   /* Locate the table which we want to delete.  This table has to be
 332   ** put in an SrcList structure because some of the subroutines we
 333   ** will be calling are designed to work with multiple tables and expect
 334   ** an SrcList* parameter instead of just a Table* parameter.
 335   */
 336   pTab = sqlite3SrcListLookup(pParse, pTabList);
 337   if( pTab==0 )  goto delete_from_cleanup;
 338
 339   /* Figure out if we have any triggers and if the table being
 340   ** deleted from is a view
 341   */
 342 #ifndef SQLITE_OMIT_TRIGGER
 343   pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
 344   isView = IsView(pTab);
 345 #else
 346 # define pTrigger 0
 347 # define isView 0
 348 #endif
 349   bComplex = pTrigger || sqlite3FkRequired(pParse, pTab, 0, 0);
 350 #ifdef SQLITE_OMIT_VIEW
 351 # undef isView
 352 # define isView 0
 353 #endif
 354
 355 #if TREETRACE_ENABLED
 356   if( sqlite3TreeTrace & 0x10000 ){
 357     sqlite3TreeViewLine(0, "In sqlite3Delete() at %s:%d", __FILE__, __LINE__);
 358     sqlite3TreeViewDelete(pParse->pWith, pTabList, pWhere,
 359                           pOrderBy, pLimit, pTrigger);
 360   }
 361 #endif
 362
 363 #ifdef SQLITE_ENABLE_UPDATE_DELETE_LIMIT
 364   if( !isView ){
 365     pWhere = sqlite3LimitWhere(
 366         pParse, pTabList, pWhere, pOrderBy, pLimit, "DELETE"
 367     );
 368     pOrderBy = 0;
 369     pLimit = 0;
 370   }
 371 #endif
 372
 373   /* If pTab is really a view, make sure it has been initialized.
 374   */
 375   if( sqlite3ViewGetColumnNames(pParse, pTab) ){
 376     goto delete_from_cleanup;
 377   }
 378
 379   if( sqlite3IsReadOnly(pParse, pTab, pTrigger) ){
 380     goto delete_from_cleanup;
 381   }
 382   iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
 383   assert( iDb<db->nDb );
 384   rcauth = sqlite3AuthCheck(pParse, SQLITE_DELETE, pTab->zName, 0,
 385                             db->aDb[iDb].zDbSName);
 386   assert( rcauth==SQLITE_OK || rcauth==SQLITE_DENY || rcauth==SQLITE_IGNORE );
 387   if( rcauth==SQLITE_DENY ){
 388     goto delete_from_cleanup;
 389   }
 390   assert(!isView || pTrigger);
 391
 392   /* Assign cursor numbers to the table and all its indices.
 393   */
 394   assert( pTabList->nSrc==1 );
 395   iTabCur = pTabList->a[0].iCursor = pParse->nTab++;
 396   for(nIdx=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, nIdx++){
 397     pParse->nTab++;
 398   }
 399
 400   /* Start the view context
 401   */
 402   if( isView ){
 403     sqlite3AuthContextPush(pParse, &sContext, pTab->zName);
 404   }
 405
 406   /* Begin generating code.
 407   */
 408   v = sqlite3GetVdbe(pParse);
 409   if( v==0 ){
 410     goto delete_from_cleanup;
 411   }
 412   if( pParse->nested==0 ) sqlite3VdbeCountChanges(v);
 413   sqlite3BeginWriteOperation(pParse, bComplex, iDb);
 414
 415   /* If we are trying to delete from a view, realize that view into
 416   ** an ephemeral table.
 417   */
 418 #if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
 419   if( isView ){
 420     sqlite3MaterializeView(pParse, pTab,
 421         pWhere, pOrderBy, pLimit, iTabCur
 422     );
 423     iDataCur = iIdxCur = iTabCur;
 424     pOrderBy = 0;
 425     pLimit = 0;
 426   }
 427 #endif
 428
 429   /* Resolve the column names in the WHERE clause.
 430   */
 431   memset(&sNC, 0, sizeof(sNC));
 432   sNC.pParse = pParse;
 433   sNC.pSrcList = pTabList;
 434   if( sqlite3ResolveExprNames(&sNC, pWhere) ){
 435     goto delete_from_cleanup;
 436   }
 437
 438   /* Initialize the counter of the number of rows deleted, if
 439   ** we are counting rows.
 440   */
 441   if( (db->flags & SQLITE_CountRows)!=0
 442    && !pParse->nested
 443    && !pParse->pTriggerTab
 444    && !pParse->bReturning
 445   ){
 446     memCnt = ++pParse->nMem;
 447     sqlite3VdbeAddOp2(v, OP_Integer, 0, memCnt);
 448   }
 449
 450 #ifndef SQLITE_OMIT_TRUNCATE_OPTIMIZATION
 451   /* Special case: A DELETE without a WHERE clause deletes everything.
 452   ** It is easier just to erase the whole table. Prior to version 3.6.5,
 453   ** this optimization caused the row change count (the value returned by
 454   ** API function sqlite3_count_changes) to be set incorrectly.
 455   **
 456   ** The "rcauth==SQLITE_OK" terms is the
 457   ** IMPLEMENTATION-OF: R-17228-37124 If the action code is SQLITE_DELETE and
 458   ** the callback returns SQLITE_IGNORE then the DELETE operation proceeds but
 459   ** the truncate optimization is disabled and all rows are deleted
 460   ** individually.
 461   */
 462   if( rcauth==SQLITE_OK
 463    && pWhere==0
 464    && !bComplex
 465    && !IsVirtual(pTab)
 466 #ifdef SQLITE_ENABLE_PREUPDATE_HOOK
 467    && db->xPreUpdateCallback==0
 468 #endif
 469   ){
 470     assert( !isView );
 471     sqlite3TableLock(pParse, iDb, pTab->tnum, 1, pTab->zName);
 472     if( HasRowid(pTab) ){
 473       sqlite3VdbeAddOp4(v, OP_Clear, pTab->tnum, iDb, memCnt ? memCnt : -1,
 474                         pTab->zName, P4_STATIC);
 475     }
 476     for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
 477       assert( pIdx->pSchema==pTab->pSchema );
 478       if( IsPrimaryKeyIndex(pIdx) && !HasRowid(pTab) ){
 479         sqlite3VdbeAddOp3(v, OP_Clear, pIdx->tnum, iDb, memCnt ? memCnt : -1);
 480       }else{
 481         sqlite3VdbeAddOp2(v, OP_Clear, pIdx->tnum, iDb);
 482       }
 483     }
 484   }else
 485 #endif /* SQLITE_OMIT_TRUNCATE_OPTIMIZATION */
 486   {
 487     u16 wcf = WHERE_ONEPASS_DESIRED|WHERE_DUPLICATES_OK;
 488     if( sNC.ncFlags & NC_Subquery ) bComplex = 1;
 489     wcf |= (bComplex ? 0 : WHERE_ONEPASS_MULTIROW);
 490     if( HasRowid(pTab) ){
 491       /* For a rowid table, initialize the RowSet to an empty set */
 492       pPk = 0;
 493       nPk = 1;
 494       iRowSet = ++pParse->nMem;
 495       sqlite3VdbeAddOp2(v, OP_Null, 0, iRowSet);
 496     }else{
 497       /* For a WITHOUT ROWID table, create an ephemeral table used to
 498       ** hold all primary keys for rows to be deleted. */
 499       pPk = sqlite3PrimaryKeyIndex(pTab);
 500       assert( pPk!=0 );
 501       nPk = pPk->nKeyCol;
 502       iPk = pParse->nMem+1;
 503       pParse->nMem += nPk;
 504       iEphCur = pParse->nTab++;
 505       addrEphOpen = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, iEphCur, nPk);
 506       sqlite3VdbeSetP4KeyInfo(pParse, pPk);
 507     }
 508
 509     /* Construct a query to find the rowid or primary key for every row
 510     ** to be deleted, based on the WHERE clause. Set variable eOnePass
 511     ** to indicate the strategy used to implement this delete:
 512     **
 513     **  ONEPASS_OFF:    Two-pass approach - use a FIFO for rowids/PK values.
 514     **  ONEPASS_SINGLE: One-pass approach - at most one row deleted.
 515     **  ONEPASS_MULTI:  One-pass approach - any number of rows may be deleted.
 516     */
 517     pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, 0,0,wcf,iTabCur+1);
 518     if( pWInfo==0 ) goto delete_from_cleanup;
 519     eOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass);
 520     assert( IsVirtual(pTab)==0 || eOnePass!=ONEPASS_MULTI );
 521     assert( IsVirtual(pTab) || bComplex || eOnePass!=ONEPASS_OFF );
 522     if( eOnePass!=ONEPASS_SINGLE ) sqlite3MultiWrite(pParse);
 523     if( sqlite3WhereUsesDeferredSeek(pWInfo) ){
 524       sqlite3VdbeAddOp1(v, OP_FinishSeek, iTabCur);
 525     }
 526
 527     /* Keep track of the number of rows to be deleted */
 528     if( memCnt ){
 529       sqlite3VdbeAddOp2(v, OP_AddImm, memCnt, 1);
 530     }
 531
 532     /* Extract the rowid or primary key for the current row */
 533     if( pPk ){
 534       for(i=0; i<nPk; i++){
 535         assert( pPk->aiColumn[i]>=0 );
 536         sqlite3ExprCodeGetColumnOfTable(v, pTab, iTabCur,
 537                                         pPk->aiColumn[i], iPk+i);
 538       }
 539       iKey = iPk;
 540     }else{
 541       iKey = ++pParse->nMem;
 542       sqlite3ExprCodeGetColumnOfTable(v, pTab, iTabCur, -1, iKey);
 543     }
 544
 545     if( eOnePass!=ONEPASS_OFF ){
 546       /* For ONEPASS, no need to store the rowid/primary-key. There is only
 547       ** one, so just keep it in its register(s) and fall through to the
 548       ** delete code.  */
 549       nKey = nPk; /* OP_Found will use an unpacked key */
 550       aToOpen = sqlite3DbMallocRawNN(db, nIdx+2);
 551       if( aToOpen==0 ){
 552         sqlite3WhereEnd(pWInfo);
 553         goto delete_from_cleanup;
 554       }
 555       memset(aToOpen, 1, nIdx+1);
 556       aToOpen[nIdx+1] = 0;
 557       if( aiCurOnePass[0]>=0 ) aToOpen[aiCurOnePass[0]-iTabCur] = 0;
 558       if( aiCurOnePass[1]>=0 ) aToOpen[aiCurOnePass[1]-iTabCur] = 0;
 559       if( addrEphOpen ) sqlite3VdbeChangeToNoop(v, addrEphOpen);
 560       addrBypass = sqlite3VdbeMakeLabel(pParse);
 561     }else{
 562       if( pPk ){
 563         /* Add the PK key for this row to the temporary table */
 564         iKey = ++pParse->nMem;
 565         nKey = 0;   /* Zero tells OP_Found to use a composite key */
 566         sqlite3VdbeAddOp4(v, OP_MakeRecord, iPk, nPk, iKey,
 567             sqlite3IndexAffinityStr(pParse->db, pPk), nPk);
 568         sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iEphCur, iKey, iPk, nPk);
 569       }else{
 570         /* Add the rowid of the row to be deleted to the RowSet */
 571         nKey = 1;  /* OP_DeferredSeek always uses a single rowid */
 572         sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, iKey);
 573       }
 574       sqlite3WhereEnd(pWInfo);
 575     }
 576
 577     /* Unless this is a view, open cursors for the table we are
 578     ** deleting from and all its indices. If this is a view, then the
 579     ** only effect this statement has is to fire the INSTEAD OF
 580     ** triggers.
 581     */
 582     if( !isView ){
 583       int iAddrOnce = 0;
 584       if( eOnePass==ONEPASS_MULTI ){
 585         iAddrOnce = sqlite3VdbeAddOp0(v, OP_Once); VdbeCoverage(v);
 586       }
 587       testcase( IsVirtual(pTab) );
 588       sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenWrite, OPFLAG_FORDELETE,
 589                                  iTabCur, aToOpen, &iDataCur, &iIdxCur);
 590       assert( pPk || IsVirtual(pTab) || iDataCur==iTabCur );
 591       assert( pPk || IsVirtual(pTab) || iIdxCur==iDataCur+1 );
 592       if( eOnePass==ONEPASS_MULTI ){
 593         sqlite3VdbeJumpHereOrPopInst(v, iAddrOnce);
 594       }
 595     }
 596
 597     /* Set up a loop over the rowids/primary-keys that were found in the
 598     ** where-clause loop above.
 599     */
 600     if( eOnePass!=ONEPASS_OFF ){
 601       assert( nKey==nPk );  /* OP_Found will use an unpacked key */
 602       if( !IsVirtual(pTab) && aToOpen[iDataCur-iTabCur] ){
 603         assert( pPk!=0 || IsView(pTab) );
 604         sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, addrBypass, iKey, nKey);
 605         VdbeCoverage(v);
 606       }
 607     }else if( pPk ){
 608       addrLoop = sqlite3VdbeAddOp1(v, OP_Rewind, iEphCur); VdbeCoverage(v);
 609       if( IsVirtual(pTab) ){
 610         sqlite3VdbeAddOp3(v, OP_Column, iEphCur, 0, iKey);
 611       }else{
 612         sqlite3VdbeAddOp2(v, OP_RowData, iEphCur, iKey);
 613       }
 614       assert( nKey==0 );  /* OP_Found will use a composite key */
 615     }else{
 616       addrLoop = sqlite3VdbeAddOp3(v, OP_RowSetRead, iRowSet, 0, iKey);
 617       VdbeCoverage(v);
 618       assert( nKey==1 );
 619     }
 620
 621     /* Delete the row */
 622 #ifndef SQLITE_OMIT_VIRTUALTABLE
 623     if( IsVirtual(pTab) ){
 624       const char *pVTab = (const char *)sqlite3GetVTable(db, pTab);
 625       sqlite3VtabMakeWritable(pParse, pTab);
 626       assert( eOnePass==ONEPASS_OFF || eOnePass==ONEPASS_SINGLE );
 627       sqlite3MayAbort(pParse);
 628       if( eOnePass==ONEPASS_SINGLE ){
 629         sqlite3VdbeAddOp1(v, OP_Close, iTabCur);
 630         if( sqlite3IsToplevel(pParse) ){
 631           pParse->isMultiWrite = 0;
 632         }
 633       }
 634       sqlite3VdbeAddOp4(v, OP_VUpdate, 0, 1, iKey, pVTab, P4_VTAB);
 635       sqlite3VdbeChangeP5(v, OE_Abort);
 636     }else
 637 #endif
 638     {
 639       int count = (pParse->nested==0);    /* True to count changes */
 640       sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
 641           iKey, nKey, count, OE_Default, eOnePass, aiCurOnePass[1]);
 642     }
 643
 644     /* End of the loop over all rowids/primary-keys. */
 645     if( eOnePass!=ONEPASS_OFF ){
 646       sqlite3VdbeResolveLabel(v, addrBypass);
 647       sqlite3WhereEnd(pWInfo);
 648     }else if( pPk ){
 649       sqlite3VdbeAddOp2(v, OP_Next, iEphCur, addrLoop+1); VdbeCoverage(v);
 650       sqlite3VdbeJumpHere(v, addrLoop);
 651     }else{
 652       sqlite3VdbeGoto(v, addrLoop);
 653       sqlite3VdbeJumpHere(v, addrLoop);
 654     }
 655   } /* End non-truncate path */
 656
 657   /* Update the sqlite_sequence table by storing the content of the
 658   ** maximum rowid counter values recorded while inserting into
 659   ** autoincrement tables.
 660   */
 661   if( pParse->nested==0 && pParse->pTriggerTab==0 ){
 662     sqlite3AutoincrementEnd(pParse);
 663   }
 664
 665   /* Return the number of rows that were deleted. If this routine is
 666   ** generating code because of a call to sqlite3NestedParse(), do not
 667   ** invoke the callback function.
 668   */
 669   if( memCnt ){
 670     sqlite3CodeChangeCount(v, memCnt, "rows deleted");
 671   }
 672
 673 delete_from_cleanup:
 674   sqlite3AuthContextPop(&sContext);
 675   sqlite3SrcListDelete(db, pTabList);
 676   sqlite3ExprDelete(db, pWhere);
 677 #if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT)
 678   sqlite3ExprListDelete(db, pOrderBy);
 679   sqlite3ExprDelete(db, pLimit);
 680 #endif
 681   if( aToOpen ) sqlite3DbNNFreeNN(db, aToOpen);
 682   return;
 683 }
 684 /* Make sure "isView" and other macros defined above are undefined. Otherwise
 685 ** they may interfere with compilation of other functions in this file
 686 ** (or in another file, if this file becomes part of the amalgamation).  */
 687 #ifdef isView
 688  #undef isView
 689 #endif
 690 #ifdef pTrigger
 691  #undef pTrigger
 692 #endif
 693
 694 /*
 695 ** This routine generates VDBE code that causes a single row of a
 696 ** single table to be deleted.  Both the original table entry and
 697 ** all indices are removed.
 698 **
 699 ** Preconditions:
 700 **
 701 **   1.  iDataCur is an open cursor on the btree that is the canonical data
 702 **       store for the table.  (This will be either the table itself,
 703 **       in the case of a rowid table, or the PRIMARY KEY index in the case
 704 **       of a WITHOUT ROWID table.)
 705 **
 706 **   2.  Read/write cursors for all indices of pTab must be open as
 707 **       cursor number iIdxCur+i for the i-th index.
 708 **
 709 **   3.  The primary key for the row to be deleted must be stored in a
 710 **       sequence of nPk memory cells starting at iPk.  If nPk==0 that means
 711 **       that a search record formed from OP_MakeRecord is contained in the
 712 **       single memory location iPk.
 713 **
 714 ** eMode:
 715 **   Parameter eMode may be passed either ONEPASS_OFF (0), ONEPASS_SINGLE, or
 716 **   ONEPASS_MULTI.  If eMode is not ONEPASS_OFF, then the cursor
 717 **   iDataCur already points to the row to delete. If eMode is ONEPASS_OFF
 718 **   then this function must seek iDataCur to the entry identified by iPk
 719 **   and nPk before reading from it.
 720 **
 721 **   If eMode is ONEPASS_MULTI, then this call is being made as part
 722 **   of a ONEPASS delete that affects multiple rows. In this case, if
 723 **   iIdxNoSeek is a valid cursor number (>=0) and is not the same as
 724 **   iDataCur, then its position should be preserved following the delete
 725 **   operation. Or, if iIdxNoSeek is not a valid cursor number, the
 726 **   position of iDataCur should be preserved instead.
 727 **
 728 ** iIdxNoSeek:
 729 **   If iIdxNoSeek is a valid cursor number (>=0) not equal to iDataCur,
 730 **   then it identifies an index cursor (from within array of cursors
 731 **   starting at iIdxCur) that already points to the index entry to be deleted.
 732 **   Except, this optimization is disabled if there are BEFORE triggers since
 733 **   the trigger body might have moved the cursor.
 734 */
 735 void sqlite3GenerateRowDelete(
 736   Parse *pParse,     /* Parsing context */
 737   Table *pTab,       /* Table containing the row to be deleted */
 738   Trigger *pTrigger, /* List of triggers to (potentially) fire */
 739   int iDataCur,      /* Cursor from which column data is extracted */
 740   int iIdxCur,       /* First index cursor */
 741   int iPk,           /* First memory cell containing the PRIMARY KEY */
 742   i16 nPk,           /* Number of PRIMARY KEY memory cells */
 743   u8 count,          /* If non-zero, increment the row change counter */
 744   u8 onconf,         /* Default ON CONFLICT policy for triggers */
 745   u8 eMode,          /* ONEPASS_OFF, _SINGLE, or _MULTI.  See above */
 746   int iIdxNoSeek     /* Cursor number of cursor that does not need seeking */
 747 ){
 748   Vdbe *v = pParse->pVdbe;        /* Vdbe */
 749   int iOld = 0;                   /* First register in OLD.* array */
 750   int iLabel;                     /* Label resolved to end of generated code */
 751   u8 opSeek;                      /* Seek opcode */
 752
 753   /* Vdbe is guaranteed to have been allocated by this stage. */
 754   assert( v );
 755   VdbeModuleComment((v, "BEGIN: GenRowDel(%d,%d,%d,%d)",
 756                          iDataCur, iIdxCur, iPk, (int)nPk));
 757
 758   /* Seek cursor iCur to the row to delete. If this row no longer exists
 759   ** (this can happen if a trigger program has already deleted it), do
 760   ** not attempt to delete it or fire any DELETE triggers.  */
 761   iLabel = sqlite3VdbeMakeLabel(pParse);
 762   opSeek = HasRowid(pTab) ? OP_NotExists : OP_NotFound;
 763   if( eMode==ONEPASS_OFF ){
 764     sqlite3VdbeAddOp4Int(v, opSeek, iDataCur, iLabel, iPk, nPk);
 765     VdbeCoverageIf(v, opSeek==OP_NotExists);
 766     VdbeCoverageIf(v, opSeek==OP_NotFound);
 767   }
 768
 769   /* If there are any triggers to fire, allocate a range of registers to
 770   ** use for the old.* references in the triggers.  */
 771   if( sqlite3FkRequired(pParse, pTab, 0, 0) || pTrigger ){
 772     u32 mask;                     /* Mask of OLD.* columns in use */
 773     int iCol;                     /* Iterator used while populating OLD.* */
 774     int addrStart;                /* Start of BEFORE trigger programs */
 775
 776     /* TODO: Could use temporary registers here. Also could attempt to
 777     ** avoid copying the contents of the rowid register.  */
 778     mask = sqlite3TriggerColmask(
 779         pParse, pTrigger, 0, 0, TRIGGER_BEFORE|TRIGGER_AFTER, pTab, onconf
 780     );
 781     mask |= sqlite3FkOldmask(pParse, pTab);
 782     iOld = pParse->nMem+1;
 783     pParse->nMem += (1 + pTab->nCol);
 784
 785     /* Populate the OLD.* pseudo-table register array. These values will be
 786     ** used by any BEFORE and AFTER triggers that exist.  */
 787     sqlite3VdbeAddOp2(v, OP_Copy, iPk, iOld);
 788     for(iCol=0; iCol<pTab->nCol; iCol++){
 789       testcase( mask!=0xffffffff && iCol==31 );
 790       testcase( mask!=0xffffffff && iCol==32 );
 791       if( mask==0xffffffff || (iCol<=31 && (mask & MASKBIT32(iCol))!=0) ){
 792         int kk = sqlite3TableColumnToStorage(pTab, iCol);
 793         sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, iCol, iOld+kk+1);
 794       }
 795     }
 796
 797     /* Invoke BEFORE DELETE trigger programs. */
 798     addrStart = sqlite3VdbeCurrentAddr(v);
 799     sqlite3CodeRowTrigger(pParse, pTrigger,
 800         TK_DELETE, 0, TRIGGER_BEFORE, pTab, iOld, onconf, iLabel
 801     );
 802
 803     /* If any BEFORE triggers were coded, then seek the cursor to the
 804     ** row to be deleted again. It may be that the BEFORE triggers moved
 805     ** the cursor or already deleted the row that the cursor was
 806     ** pointing to.
 807     **
 808     ** Also disable the iIdxNoSeek optimization since the BEFORE trigger
 809     ** may have moved that cursor.
 810     */
 811     if( addrStart<sqlite3VdbeCurrentAddr(v) ){
 812       sqlite3VdbeAddOp4Int(v, opSeek, iDataCur, iLabel, iPk, nPk);
 813       VdbeCoverageIf(v, opSeek==OP_NotExists);
 814       VdbeCoverageIf(v, opSeek==OP_NotFound);
 815       testcase( iIdxNoSeek>=0 );
 816       iIdxNoSeek = -1;
 817     }
 818
 819     /* Do FK processing. This call checks that any FK constraints that
 820     ** refer to this table (i.e. constraints attached to other tables)
 821     ** are not violated by deleting this row.  */
 822     sqlite3FkCheck(pParse, pTab, iOld, 0, 0, 0);
 823   }
 824
 825   /* Delete the index and table entries. Skip this step if pTab is really
 826   ** a view (in which case the only effect of the DELETE statement is to
 827   ** fire the INSTEAD OF triggers).
 828   **
 829   ** If variable 'count' is non-zero, then this OP_Delete instruction should
 830   ** invoke the update-hook. The pre-update-hook, on the other hand should
 831   ** be invoked unless table pTab is a system table. The difference is that
 832   ** the update-hook is not invoked for rows removed by REPLACE, but the
 833   ** pre-update-hook is.
 834   */
 835   if( !IsView(pTab) ){
 836     u8 p5 = 0;
 837     sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur,0,iIdxNoSeek);
 838     sqlite3VdbeAddOp2(v, OP_Delete, iDataCur, (count?OPFLAG_NCHANGE:0));
 839     if( pParse->nested==0 || 0==sqlite3_stricmp(pTab->zName, "sqlite_stat1") ){
 840       sqlite3VdbeAppendP4(v, (char*)pTab, P4_TABLE);
 841     }
 842     if( eMode!=ONEPASS_OFF ){
 843       sqlite3VdbeChangeP5(v, OPFLAG_AUXDELETE);
 844     }
 845     if( iIdxNoSeek>=0 && iIdxNoSeek!=iDataCur ){
 846       sqlite3VdbeAddOp1(v, OP_Delete, iIdxNoSeek);
 847     }
 848     if( eMode==ONEPASS_MULTI ) p5 |= OPFLAG_SAVEPOSITION;
 849     sqlite3VdbeChangeP5(v, p5);
 850   }
 851
 852   /* Do any ON CASCADE, SET NULL or SET DEFAULT operations required to
 853   ** handle rows (possibly in other tables) that refer via a foreign key
 854   ** to the row just deleted. */
 855   sqlite3FkActions(pParse, pTab, 0, iOld, 0, 0);
 856
 857   /* Invoke AFTER DELETE trigger programs. */
 858   sqlite3CodeRowTrigger(pParse, pTrigger,
 859       TK_DELETE, 0, TRIGGER_AFTER, pTab, iOld, onconf, iLabel
 860   );
 861
 862   /* Jump here if the row had already been deleted before any BEFORE
 863   ** trigger programs were invoked. Or if a trigger program throws a
 864   ** RAISE(IGNORE) exception.  */
 865   sqlite3VdbeResolveLabel(v, iLabel);
 866   VdbeModuleComment((v, "END: GenRowDel()"));
 867 }
 868
 869 /*
 870 ** This routine generates VDBE code that causes the deletion of all
 871 ** index entries associated with a single row of a single table, pTab
 872 **
 873 ** Preconditions:
 874 **
 875 **   1.  A read/write cursor "iDataCur" must be open on the canonical storage
 876 **       btree for the table pTab.  (This will be either the table itself
 877 **       for rowid tables or to the primary key index for WITHOUT ROWID
 878 **       tables.)
 879 **
 880 **   2.  Read/write cursors for all indices of pTab must be open as
 881 **       cursor number iIdxCur+i for the i-th index.  (The pTab->pIndex
 882 **       index is the 0-th index.)
 883 **
 884 **   3.  The "iDataCur" cursor must be already be positioned on the row
 885 **       that is to be deleted.
 886 */
 887 void sqlite3GenerateRowIndexDelete(
 888   Parse *pParse,     /* Parsing and code generating context */
 889   Table *pTab,       /* Table containing the row to be deleted */
 890   int iDataCur,      /* Cursor of table holding data. */
 891   int iIdxCur,       /* First index cursor */
 892   int *aRegIdx,      /* Only delete if aRegIdx!=0 && aRegIdx[i]>0 */
 893   int iIdxNoSeek     /* Do not delete from this cursor */
 894 ){
 895   int i;             /* Index loop counter */
 896   int r1 = -1;       /* Register holding an index key */
 897   int iPartIdxLabel; /* Jump destination for skipping partial index entries */
 898   Index *pIdx;       /* Current index */
 899   Index *pPrior = 0; /* Prior index */
 900   Vdbe *v;           /* The prepared statement under construction */
 901   Index *pPk;        /* PRIMARY KEY index, or NULL for rowid tables */
 902
 903   v = pParse->pVdbe;
 904   pPk = HasRowid(pTab) ? 0 : sqlite3PrimaryKeyIndex(pTab);
 905   for(i=0, pIdx=pTab->pIndex; pIdx; i++, pIdx=pIdx->pNext){
 906     assert( iIdxCur+i!=iDataCur || pPk==pIdx );
 907     if( aRegIdx!=0 && aRegIdx[i]==0 ) continue;
 908     if( pIdx==pPk ) continue;
 909     if( iIdxCur+i==iIdxNoSeek ) continue;
 910     VdbeModuleComment((v, "GenRowIdxDel for %s", pIdx->zName));
 911     r1 = sqlite3GenerateIndexKey(pParse, pIdx, iDataCur, 0, 1,
 912         &iPartIdxLabel, pPrior, r1);
 913     sqlite3VdbeAddOp3(v, OP_IdxDelete, iIdxCur+i, r1,
 914         pIdx->uniqNotNull ? pIdx->nKeyCol : pIdx->nColumn);
 915     sqlite3VdbeChangeP5(v, 1);  /* Cause IdxDelete to error if no entry found */
 916     sqlite3ResolvePartIdxLabel(pParse, iPartIdxLabel);
 917     pPrior = pIdx;
 918   }
 919 }
 920
 921 /*
 922 ** Generate code that will assemble an index key and stores it in register
 923 ** regOut.  The key with be for index pIdx which is an index on pTab.
 924 ** iCur is the index of a cursor open on the pTab table and pointing to
 925 ** the entry that needs indexing.  If pTab is a WITHOUT ROWID table, then
 926 ** iCur must be the cursor of the PRIMARY KEY index.
 927 **
 928 ** Return a register number which is the first in a block of
 929 ** registers that holds the elements of the index key.  The
 930 ** block of registers has already been deallocated by the time
 931 ** this routine returns.
 932 **
 933 ** If *piPartIdxLabel is not NULL, fill it in with a label and jump
 934 ** to that label if pIdx is a partial index that should be skipped.
 935 ** The label should be resolved using sqlite3ResolvePartIdxLabel().
 936 ** A partial index should be skipped if its WHERE clause evaluates
 937 ** to false or null.  If pIdx is not a partial index, *piPartIdxLabel
 938 ** will be set to zero which is an empty label that is ignored by
 939 ** sqlite3ResolvePartIdxLabel().
 940 **
 941 ** The pPrior and regPrior parameters are used to implement a cache to
 942 ** avoid unnecessary register loads.  If pPrior is not NULL, then it is
 943 ** a pointer to a different index for which an index key has just been
 944 ** computed into register regPrior.  If the current pIdx index is generating
 945 ** its key into the same sequence of registers and if pPrior and pIdx share
 946 ** a column in common, then the register corresponding to that column already
 947 ** holds the correct value and the loading of that register is skipped.
 948 ** This optimization is helpful when doing a DELETE or an INTEGRITY_CHECK
 949 ** on a table with multiple indices, and especially with the ROWID or
 950 ** PRIMARY KEY columns of the index.
 951 */
 952 int sqlite3GenerateIndexKey(
 953   Parse *pParse,       /* Parsing context */
 954   Index *pIdx,         /* The index for which to generate a key */
 955   int iDataCur,        /* Cursor number from which to take column data */
 956   int regOut,          /* Put the new key into this register if not 0 */
 957   int prefixOnly,      /* Compute only a unique prefix of the key */
 958   int *piPartIdxLabel, /* OUT: Jump to this label to skip partial index */
 959   Index *pPrior,       /* Previously generated index key */
 960   int regPrior         /* Register holding previous generated key */
 961 ){
 962   Vdbe *v = pParse->pVdbe;
 963   int j;
 964   int regBase;
 965   int nCol;
 966
 967   if( piPartIdxLabel ){
 968     if( pIdx->pPartIdxWhere ){
 969       *piPartIdxLabel = sqlite3VdbeMakeLabel(pParse);
 970       pParse->iSelfTab = iDataCur + 1;
 971       sqlite3ExprIfFalseDup(pParse, pIdx->pPartIdxWhere, *piPartIdxLabel,
 972                             SQLITE_JUMPIFNULL);
 973       pParse->iSelfTab = 0;
 974       pPrior = 0; /* Ticket a9efb42811fa41ee 2019-11-02;
 975                   ** pPartIdxWhere may have corrupted regPrior registers */
 976     }else{
 977       *piPartIdxLabel = 0;
 978     }
 979   }
 980   nCol = (prefixOnly && pIdx->uniqNotNull) ? pIdx->nKeyCol : pIdx->nColumn;
 981   regBase = sqlite3GetTempRange(pParse, nCol);
 982   if( pPrior && (regBase!=regPrior || pPrior->pPartIdxWhere) ) pPrior = 0;
 983   for(j=0; j<nCol; j++){
 984     if( pPrior
 985      && pPrior->aiColumn[j]==pIdx->aiColumn[j]
 986      && pPrior->aiColumn[j]!=XN_EXPR
 987     ){
 988       /* This column was already computed by the previous index */
 989       continue;
 990     }
 991     sqlite3ExprCodeLoadIndexColumn(pParse, pIdx, iDataCur, j, regBase+j);
 992     if( pIdx->aiColumn[j]>=0 ){
 993       /* If the column affinity is REAL but the number is an integer, then it
 994       ** might be stored in the table as an integer (using a compact
 995       ** representation) then converted to REAL by an OP_RealAffinity opcode.
 996       ** But we are getting ready to store this value back into an index, where
 997       ** it should be converted by to INTEGER again.  So omit the
 998       ** OP_RealAffinity opcode if it is present */
 999       sqlite3VdbeDeletePriorOpcode(v, OP_RealAffinity);
1000     }
1001   }
1002   if( regOut ){
1003     sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regOut);
1004   }
1005   sqlite3ReleaseTempRange(pParse, regBase, nCol);
1006   return regBase;
1007 }
1008
1009 /*
1010 ** If a prior call to sqlite3GenerateIndexKey() generated a jump-over label
1011 ** because it was a partial index, then this routine should be called to
1012 ** resolve that label.
1013 */
1014 void sqlite3ResolvePartIdxLabel(Parse *pParse, int iLabel){
1015   if( iLabel ){
1016     sqlite3VdbeResolveLabel(pParse->pVdbe, iLabel);
1017   }
1018 }