src/whereexpr.c

   1 /*
   2 ** 2015-06-08
   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 module contains C code that generates VDBE code used to process
  13 ** the WHERE clause of SQL statements.
  14 **
  15 ** This file was originally part of where.c but was split out to improve
  16 ** readability and editabiliity.  This file contains utility routines for
  17 ** analyzing Expr objects in the WHERE clause.
  18 */
  19 #include "sqliteInt.h"
  20 #include "whereInt.h"
  21
  22 /* Forward declarations */
  23 static void exprAnalyze(SrcList*, WhereClause*, int);
  24
  25 /*
  26 ** Deallocate all memory associated with a WhereOrInfo object.
  27 */
  28 static void whereOrInfoDelete(sqlite3 *db, WhereOrInfo *p){
  29   sqlite3WhereClauseClear(&p->wc);
  30   sqlite3DbFree(db, p);
  31 }
  32
  33 /*
  34 ** Deallocate all memory associated with a WhereAndInfo object.
  35 */
  36 static void whereAndInfoDelete(sqlite3 *db, WhereAndInfo *p){
  37   sqlite3WhereClauseClear(&p->wc);
  38   sqlite3DbFree(db, p);
  39 }
  40
  41 /*
  42 ** Add a single new WhereTerm entry to the WhereClause object pWC.
  43 ** The new WhereTerm object is constructed from Expr p and with wtFlags.
  44 ** The index in pWC->a[] of the new WhereTerm is returned on success.
  45 ** 0 is returned if the new WhereTerm could not be added due to a memory
  46 ** allocation error.  The memory allocation failure will be recorded in
  47 ** the db->mallocFailed flag so that higher-level functions can detect it.
  48 **
  49 ** This routine will increase the size of the pWC->a[] array as necessary.
  50 **
  51 ** If the wtFlags argument includes TERM_DYNAMIC, then responsibility
  52 ** for freeing the expression p is assumed by the WhereClause object pWC.
  53 ** This is true even if this routine fails to allocate a new WhereTerm.
  54 **
  55 ** WARNING:  This routine might reallocate the space used to store
  56 ** WhereTerms.  All pointers to WhereTerms should be invalidated after
  57 ** calling this routine.  Such pointers may be reinitialized by referencing
  58 ** the pWC->a[] array.
  59 */
  60 static int whereClauseInsert(WhereClause *pWC, Expr *p, u16 wtFlags){
  61   WhereTerm *pTerm;
  62   int idx;
  63   testcase( wtFlags & TERM_VIRTUAL );
  64   if( pWC->nTerm>=pWC->nSlot ){
  65     WhereTerm *pOld = pWC->a;
  66     sqlite3 *db = pWC->pWInfo->pParse->db;
  67     pWC->a = sqlite3DbMallocRawNN(db, sizeof(pWC->a[0])*pWC->nSlot*2 );
  68     if( pWC->a==0 ){
  69       if( wtFlags & TERM_DYNAMIC ){
  70         sqlite3ExprDelete(db, p);
  71       }
  72       pWC->a = pOld;
  73       return 0;
  74     }
  75     memcpy(pWC->a, pOld, sizeof(pWC->a[0])*pWC->nTerm);
  76     if( pOld!=pWC->aStatic ){
  77       sqlite3DbFree(db, pOld);
  78     }
  79     pWC->nSlot = sqlite3DbMallocSize(db, pWC->a)/sizeof(pWC->a[0]);
  80   }
  81   pTerm = &pWC->a[idx = pWC->nTerm++];
  82   if( p && ExprHasProperty(p, EP_Unlikely) ){
  83     pTerm->truthProb = sqlite3LogEst(p->iTable) - 270;
  84   }else{
  85     pTerm->truthProb = 1;
  86   }
  87   pTerm->pExpr = sqlite3ExprSkipCollateAndLikely(p);
  88   pTerm->wtFlags = wtFlags;
  89   pTerm->pWC = pWC;
  90   pTerm->iParent = -1;
  91   memset(&pTerm->eOperator, 0,
  92          sizeof(WhereTerm) - offsetof(WhereTerm,eOperator));
  93   return idx;
  94 }
  95
  96 /*
  97 ** Return TRUE if the given operator is one of the operators that is
  98 ** allowed for an indexable WHERE clause term.  The allowed operators are
  99 ** "=", "<", ">", "<=", ">=", "IN", "IS", and "IS NULL"
 100 */
 101 static int allowedOp(int op){
 102   assert( TK_GT>TK_EQ && TK_GT<TK_GE );
 103   assert( TK_LT>TK_EQ && TK_LT<TK_GE );
 104   assert( TK_LE>TK_EQ && TK_LE<TK_GE );
 105   assert( TK_GE==TK_EQ+4 );
 106   return op==TK_IN || (op>=TK_EQ && op<=TK_GE) || op==TK_ISNULL || op==TK_IS;
 107 }
 108
 109 /*
 110 ** Commute a comparison operator.  Expressions of the form "X op Y"
 111 ** are converted into "Y op X".
 112 */
 113 static u16 exprCommute(Parse *pParse, Expr *pExpr){
 114   if( pExpr->pLeft->op==TK_VECTOR
 115    || pExpr->pRight->op==TK_VECTOR
 116    || sqlite3BinaryCompareCollSeq(pParse, pExpr->pLeft, pExpr->pRight) !=
 117       sqlite3BinaryCompareCollSeq(pParse, pExpr->pRight, pExpr->pLeft)
 118   ){
 119     pExpr->flags ^= EP_Commuted;
 120   }
 121   SWAP(Expr*,pExpr->pRight,pExpr->pLeft);
 122   if( pExpr->op>=TK_GT ){
 123     assert( TK_LT==TK_GT+2 );
 124     assert( TK_GE==TK_LE+2 );
 125     assert( TK_GT>TK_EQ );
 126     assert( TK_GT<TK_LE );
 127     assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE );
 128     pExpr->op = ((pExpr->op-TK_GT)^2)+TK_GT;
 129   }
 130   return 0;
 131 }
 132
 133 /*
 134 ** Translate from TK_xx operator to WO_xx bitmask.
 135 */
 136 static u16 operatorMask(int op){
 137   u16 c;
 138   assert( allowedOp(op) );
 139   if( op==TK_IN ){
 140     c = WO_IN;
 141   }else if( op==TK_ISNULL ){
 142     c = WO_ISNULL;
 143   }else if( op==TK_IS ){
 144     c = WO_IS;
 145   }else{
 146     assert( (WO_EQ<<(op-TK_EQ)) < 0x7fff );
 147     c = (u16)(WO_EQ<<(op-TK_EQ));
 148   }
 149   assert( op!=TK_ISNULL || c==WO_ISNULL );
 150   assert( op!=TK_IN || c==WO_IN );
 151   assert( op!=TK_EQ || c==WO_EQ );
 152   assert( op!=TK_LT || c==WO_LT );
 153   assert( op!=TK_LE || c==WO_LE );
 154   assert( op!=TK_GT || c==WO_GT );
 155   assert( op!=TK_GE || c==WO_GE );
 156   assert( op!=TK_IS || c==WO_IS );
 157   return c;
 158 }
 159
 160
 161 #ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
 162 /*
 163 ** Check to see if the given expression is a LIKE or GLOB operator that
 164 ** can be optimized using inequality constraints.  Return TRUE if it is
 165 ** so and false if not.
 166 **
 167 ** In order for the operator to be optimizible, the RHS must be a string
 168 ** literal that does not begin with a wildcard.  The LHS must be a column
 169 ** that may only be NULL, a string, or a BLOB, never a number. (This means
 170 ** that virtual tables cannot participate in the LIKE optimization.)  The
 171 ** collating sequence for the column on the LHS must be appropriate for
 172 ** the operator.
 173 */
 174 static int isLikeOrGlob(
 175   Parse *pParse,    /* Parsing and code generating context */
 176   Expr *pExpr,      /* Test this expression */
 177   Expr **ppPrefix,  /* Pointer to TK_STRING expression with pattern prefix */
 178   int *pisComplete, /* True if the only wildcard is % in the last character */
 179   int *pnoCase      /* True if uppercase is equivalent to lowercase */
 180 ){
 181   const u8 *z = 0;           /* String on RHS of LIKE operator */
 182   Expr *pRight, *pLeft;      /* Right and left size of LIKE operator */
 183   ExprList *pList;           /* List of operands to the LIKE operator */
 184   u8 c;                      /* One character in z[] */
 185   int cnt;                   /* Number of non-wildcard prefix characters */
 186   u8 wc[4];                  /* Wildcard characters */
 187   sqlite3 *db = pParse->db;  /* Database connection */
 188   sqlite3_value *pVal = 0;
 189   int op;                    /* Opcode of pRight */
 190   int rc;                    /* Result code to return */
 191
 192   if( !sqlite3IsLikeFunction(db, pExpr, pnoCase, (char*)wc) ){
 193     return 0;
 194   }
 195 #ifdef SQLITE_EBCDIC
 196   if( *pnoCase ) return 0;
 197 #endif
 198   pList = pExpr->x.pList;
 199   pLeft = pList->a[1].pExpr;
 200
 201   pRight = sqlite3ExprSkipCollate(pList->a[0].pExpr);
 202   op = pRight->op;
 203   if( op==TK_VARIABLE && (db->flags & SQLITE_EnableQPSG)==0 ){
 204     Vdbe *pReprepare = pParse->pReprepare;
 205     int iCol = pRight->iColumn;
 206     pVal = sqlite3VdbeGetBoundValue(pReprepare, iCol, SQLITE_AFF_BLOB);
 207     if( pVal && sqlite3_value_type(pVal)==SQLITE_TEXT ){
 208       z = sqlite3_value_text(pVal);
 209     }
 210     sqlite3VdbeSetVarmask(pParse->pVdbe, iCol);
 211     assert( pRight->op==TK_VARIABLE || pRight->op==TK_REGISTER );
 212   }else if( op==TK_STRING ){
 213     z = (u8*)pRight->u.zToken;
 214   }
 215   if( z ){
 216
 217     /* Count the number of prefix characters prior to the first wildcard */
 218     cnt = 0;
 219     while( (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2] ){
 220       cnt++;
 221       if( c==wc[3] && z[cnt]!=0 ) cnt++;
 222     }
 223
 224     /* The optimization is possible only if (1) the pattern does not begin
 225     ** with a wildcard and if (2) the non-wildcard prefix does not end with
 226     ** an (illegal 0xff) character, or (3) the pattern does not consist of
 227     ** a single escape character. The second condition is necessary so
 228     ** that we can increment the prefix key to find an upper bound for the
 229     ** range search. The third is because the caller assumes that the pattern
 230     ** consists of at least one character after all escapes have been
 231     ** removed.  */
 232     if( cnt!=0 && 255!=(u8)z[cnt-1] && (cnt>1 || z[0]!=wc[3]) ){
 233       Expr *pPrefix;
 234
 235       /* A "complete" match if the pattern ends with "*" or "%" */
 236       *pisComplete = c==wc[0] && z[cnt+1]==0;
 237
 238       /* Get the pattern prefix.  Remove all escapes from the prefix. */
 239       pPrefix = sqlite3Expr(db, TK_STRING, (char*)z);
 240       if( pPrefix ){
 241         int iFrom, iTo;
 242         char *zNew = pPrefix->u.zToken;
 243         zNew[cnt] = 0;
 244         for(iFrom=iTo=0; iFrom<cnt; iFrom++){
 245           if( zNew[iFrom]==wc[3] ) iFrom++;
 246           zNew[iTo++] = zNew[iFrom];
 247         }
 248         zNew[iTo] = 0;
 249         assert( iTo>0 );
 250
 251         /* If the LHS is not an ordinary column with TEXT affinity, then the
 252         ** pattern prefix boundaries (both the start and end boundaries) must
 253         ** not look like a number.  Otherwise the pattern might be treated as
 254         ** a number, which will invalidate the LIKE optimization.
 255         **
 256         ** Getting this right has been a persistent source of bugs in the
 257         ** LIKE optimization.  See, for example:
 258         **    2018-09-10 https://sqlite.org/src/info/c94369cae9b561b1
 259         **    2019-05-02 https://sqlite.org/src/info/b043a54c3de54b28
 260         **    2019-06-10 https://sqlite.org/src/info/fd76310a5e843e07
 261         **    2019-06-14 https://sqlite.org/src/info/ce8717f0885af975
 262         **    2019-09-03 https://sqlite.org/src/info/0f0428096f17252a
 263         */
 264         if( pLeft->op!=TK_COLUMN
 265          || sqlite3ExprAffinity(pLeft)!=SQLITE_AFF_TEXT
 266          || IsVirtual(pLeft->y.pTab)  /* Value might be numeric */
 267         ){
 268           int isNum;
 269           double rDummy;
 270           isNum = sqlite3AtoF(zNew, &rDummy, iTo, SQLITE_UTF8);
 271           if( isNum<=0 ){
 272             if( iTo==1 && zNew[0]=='-' ){
 273               isNum = +1;
 274             }else{
 275               zNew[iTo-1]++;
 276               isNum = sqlite3AtoF(zNew, &rDummy, iTo, SQLITE_UTF8);
 277               zNew[iTo-1]--;
 278             }
 279           }
 280           if( isNum>0 ){
 281             sqlite3ExprDelete(db, pPrefix);
 282             sqlite3ValueFree(pVal);
 283             return 0;
 284           }
 285         }
 286       }
 287       *ppPrefix = pPrefix;
 288
 289       /* If the RHS pattern is a bound parameter, make arrangements to
 290       ** reprepare the statement when that parameter is rebound */
 291       if( op==TK_VARIABLE ){
 292         Vdbe *v = pParse->pVdbe;
 293         sqlite3VdbeSetVarmask(v, pRight->iColumn);
 294         if( *pisComplete && pRight->u.zToken[1] ){
 295           /* If the rhs of the LIKE expression is a variable, and the current
 296           ** value of the variable means there is no need to invoke the LIKE
 297           ** function, then no OP_Variable will be added to the program.
 298           ** This causes problems for the sqlite3_bind_parameter_name()
 299           ** API. To work around them, add a dummy OP_Variable here.
 300           */
 301           int r1 = sqlite3GetTempReg(pParse);
 302           sqlite3ExprCodeTarget(pParse, pRight, r1);
 303           sqlite3VdbeChangeP3(v, sqlite3VdbeCurrentAddr(v)-1, 0);
 304           sqlite3ReleaseTempReg(pParse, r1);
 305         }
 306       }
 307     }else{
 308       z = 0;
 309     }
 310   }
 311
 312   rc = (z!=0);
 313   sqlite3ValueFree(pVal);
 314   return rc;
 315 }
 316 #endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
 317
 318
 319 #ifndef SQLITE_OMIT_VIRTUALTABLE
 320 /*
 321 ** Check to see if the pExpr expression is a form that needs to be passed
 322 ** to the xBestIndex method of virtual tables.  Forms of interest include:
 323 **
 324 **          Expression                   Virtual Table Operator
 325 **          -----------------------      ---------------------------------
 326 **      1.  column MATCH expr            SQLITE_INDEX_CONSTRAINT_MATCH
 327 **      2.  column GLOB expr             SQLITE_INDEX_CONSTRAINT_GLOB
 328 **      3.  column LIKE expr             SQLITE_INDEX_CONSTRAINT_LIKE
 329 **      4.  column REGEXP expr           SQLITE_INDEX_CONSTRAINT_REGEXP
 330 **      5.  column != expr               SQLITE_INDEX_CONSTRAINT_NE
 331 **      6.  expr != column               SQLITE_INDEX_CONSTRAINT_NE
 332 **      7.  column IS NOT expr           SQLITE_INDEX_CONSTRAINT_ISNOT
 333 **      8.  expr IS NOT column           SQLITE_INDEX_CONSTRAINT_ISNOT
 334 **      9.  column IS NOT NULL           SQLITE_INDEX_CONSTRAINT_ISNOTNULL
 335 **
 336 ** In every case, "column" must be a column of a virtual table.  If there
 337 ** is a match, set *ppLeft to the "column" expression, set *ppRight to the
 338 ** "expr" expression (even though in forms (6) and (8) the column is on the
 339 ** right and the expression is on the left).  Also set *peOp2 to the
 340 ** appropriate virtual table operator.  The return value is 1 or 2 if there
 341 ** is a match.  The usual return is 1, but if the RHS is also a column
 342 ** of virtual table in forms (5) or (7) then return 2.
 343 **
 344 ** If the expression matches none of the patterns above, return 0.
 345 */
 346 static int isAuxiliaryVtabOperator(
 347   sqlite3 *db,                    /* Parsing context */
 348   Expr *pExpr,                    /* Test this expression */
 349   unsigned char *peOp2,           /* OUT: 0 for MATCH, or else an op2 value */
 350   Expr **ppLeft,                  /* Column expression to left of MATCH/op2 */
 351   Expr **ppRight                  /* Expression to left of MATCH/op2 */
 352 ){
 353   if( pExpr->op==TK_FUNCTION ){
 354     static const struct Op2 {
 355       const char *zOp;
 356       unsigned char eOp2;
 357     } aOp[] = {
 358       { "match",  SQLITE_INDEX_CONSTRAINT_MATCH },
 359       { "glob",   SQLITE_INDEX_CONSTRAINT_GLOB },
 360       { "like",   SQLITE_INDEX_CONSTRAINT_LIKE },
 361       { "regexp", SQLITE_INDEX_CONSTRAINT_REGEXP }
 362     };
 363     ExprList *pList;
 364     Expr *pCol;                     /* Column reference */
 365     int i;
 366
 367     pList = pExpr->x.pList;
 368     if( pList==0 || pList->nExpr!=2 ){
 369       return 0;
 370     }
 371
 372     /* Built-in operators MATCH, GLOB, LIKE, and REGEXP attach to a
 373     ** virtual table on their second argument, which is the same as
 374     ** the left-hand side operand in their in-fix form.
 375     **
 376     **       vtab_column MATCH expression
 377     **       MATCH(expression,vtab_column)
 378     */
 379     pCol = pList->a[1].pExpr;
 380     testcase( pCol->op==TK_COLUMN && pCol->y.pTab==0 );
 381     if( ExprIsVtab(pCol) ){
 382       for(i=0; i<ArraySize(aOp); i++){
 383         if( sqlite3StrICmp(pExpr->u.zToken, aOp[i].zOp)==0 ){
 384           *peOp2 = aOp[i].eOp2;
 385           *ppRight = pList->a[0].pExpr;
 386           *ppLeft = pCol;
 387           return 1;
 388         }
 389       }
 390     }
 391
 392     /* We can also match against the first column of overloaded
 393     ** functions where xFindFunction returns a value of at least
 394     ** SQLITE_INDEX_CONSTRAINT_FUNCTION.
 395     **
 396     **      OVERLOADED(vtab_column,expression)
 397     **
 398     ** Historically, xFindFunction expected to see lower-case function
 399     ** names.  But for this use case, xFindFunction is expected to deal
 400     ** with function names in an arbitrary case.
 401     */
 402     pCol = pList->a[0].pExpr;
 403     testcase( pCol->op==TK_COLUMN && pCol->y.pTab==0 );
 404     if( ExprIsVtab(pCol) ){
 405       sqlite3_vtab *pVtab;
 406       sqlite3_module *pMod;
 407       void (*xNotUsed)(sqlite3_context*,int,sqlite3_value**);
 408       void *pNotUsed;
 409       pVtab = sqlite3GetVTable(db, pCol->y.pTab)->pVtab;
 410       assert( pVtab!=0 );
 411       assert( pVtab->pModule!=0 );
 412       pMod = (sqlite3_module *)pVtab->pModule;
 413       if( pMod->xFindFunction!=0 ){
 414         i = pMod->xFindFunction(pVtab,2, pExpr->u.zToken, &xNotUsed, &pNotUsed);
 415         if( i>=SQLITE_INDEX_CONSTRAINT_FUNCTION ){
 416           *peOp2 = i;
 417           *ppRight = pList->a[1].pExpr;
 418           *ppLeft = pCol;
 419           return 1;
 420         }
 421       }
 422     }
 423   }else if( pExpr->op==TK_NE || pExpr->op==TK_ISNOT || pExpr->op==TK_NOTNULL ){
 424     int res = 0;
 425     Expr *pLeft = pExpr->pLeft;
 426     Expr *pRight = pExpr->pRight;
 427     testcase( pLeft->op==TK_COLUMN && pLeft->y.pTab==0 );
 428     if( ExprIsVtab(pLeft) ){
 429       res++;
 430     }
 431     testcase( pRight && pRight->op==TK_COLUMN && pRight->y.pTab==0 );
 432     if( pRight && ExprIsVtab(pRight) ){
 433       res++;
 434       SWAP(Expr*, pLeft, pRight);
 435     }
 436     *ppLeft = pLeft;
 437     *ppRight = pRight;
 438     if( pExpr->op==TK_NE ) *peOp2 = SQLITE_INDEX_CONSTRAINT_NE;
 439     if( pExpr->op==TK_ISNOT ) *peOp2 = SQLITE_INDEX_CONSTRAINT_ISNOT;
 440     if( pExpr->op==TK_NOTNULL ) *peOp2 = SQLITE_INDEX_CONSTRAINT_ISNOTNULL;
 441     return res;
 442   }
 443   return 0;
 444 }
 445 #endif /* SQLITE_OMIT_VIRTUALTABLE */
 446
 447 /*
 448 ** If the pBase expression originated in the ON or USING clause of
 449 ** a join, then transfer the appropriate markings over to derived.
 450 */
 451 static void transferJoinMarkings(Expr *pDerived, Expr *pBase){
 452   if( pDerived ){
 453     pDerived->flags |= pBase->flags & EP_FromJoin;
 454     pDerived->iRightJoinTable = pBase->iRightJoinTable;
 455   }
 456 }
 457
 458 /*
 459 ** Mark term iChild as being a child of term iParent
 460 */
 461 static void markTermAsChild(WhereClause *pWC, int iChild, int iParent){
 462   pWC->a[iChild].iParent = iParent;
 463   pWC->a[iChild].truthProb = pWC->a[iParent].truthProb;
 464   pWC->a[iParent].nChild++;
 465 }
 466
 467 /*
 468 ** Return the N-th AND-connected subterm of pTerm.  Or if pTerm is not
 469 ** a conjunction, then return just pTerm when N==0.  If N is exceeds
 470 ** the number of available subterms, return NULL.
 471 */
 472 static WhereTerm *whereNthSubterm(WhereTerm *pTerm, int N){
 473   if( pTerm->eOperator!=WO_AND ){
 474     return N==0 ? pTerm : 0;
 475   }
 476   if( N<pTerm->u.pAndInfo->wc.nTerm ){
 477     return &pTerm->u.pAndInfo->wc.a[N];
 478   }
 479   return 0;
 480 }
 481
 482 /*
 483 ** Subterms pOne and pTwo are contained within WHERE clause pWC.  The
 484 ** two subterms are in disjunction - they are OR-ed together.
 485 **
 486 ** If these two terms are both of the form:  "A op B" with the same
 487 ** A and B values but different operators and if the operators are
 488 ** compatible (if one is = and the other is <, for example) then
 489 ** add a new virtual AND term to pWC that is the combination of the
 490 ** two.
 491 **
 492 ** Some examples:
 493 **
 494 **    x<y OR x=y    -->     x<=y
 495 **    x=y OR x=y    -->     x=y
 496 **    x<=y OR x<y   -->     x<=y
 497 **
 498 ** The following is NOT generated:
 499 **
 500 **    x<y OR x>y    -->     x!=y
 501 */
 502 static void whereCombineDisjuncts(
 503   SrcList *pSrc,         /* the FROM clause */
 504   WhereClause *pWC,      /* The complete WHERE clause */
 505   WhereTerm *pOne,       /* First disjunct */
 506   WhereTerm *pTwo        /* Second disjunct */
 507 ){
 508   u16 eOp = pOne->eOperator | pTwo->eOperator;
 509   sqlite3 *db;           /* Database connection (for malloc) */
 510   Expr *pNew;            /* New virtual expression */
 511   int op;                /* Operator for the combined expression */
 512   int idxNew;            /* Index in pWC of the next virtual term */
 513
 514   if( (pOne->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return;
 515   if( (pTwo->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return;
 516   if( (eOp & (WO_EQ|WO_LT|WO_LE))!=eOp
 517    && (eOp & (WO_EQ|WO_GT|WO_GE))!=eOp ) return;
 518   assert( pOne->pExpr->pLeft!=0 && pOne->pExpr->pRight!=0 );
 519   assert( pTwo->pExpr->pLeft!=0 && pTwo->pExpr->pRight!=0 );
 520   if( sqlite3ExprCompare(0,pOne->pExpr->pLeft, pTwo->pExpr->pLeft, -1) ) return;
 521   if( sqlite3ExprCompare(0,pOne->pExpr->pRight, pTwo->pExpr->pRight,-1) )return;
 522   /* If we reach this point, it means the two subterms can be combined */
 523   if( (eOp & (eOp-1))!=0 ){
 524     if( eOp & (WO_LT|WO_LE) ){
 525       eOp = WO_LE;
 526     }else{
 527       assert( eOp & (WO_GT|WO_GE) );
 528       eOp = WO_GE;
 529     }
 530   }
 531   db = pWC->pWInfo->pParse->db;
 532   pNew = sqlite3ExprDup(db, pOne->pExpr, 0);
 533   if( pNew==0 ) return;
 534   for(op=TK_EQ; eOp!=(WO_EQ<<(op-TK_EQ)); op++){ assert( op<TK_GE ); }
 535   pNew->op = op;
 536   idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC);
 537   exprAnalyze(pSrc, pWC, idxNew);
 538 }
 539
 540 #if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
 541 /*
 542 ** Analyze a term that consists of two or more OR-connected
 543 ** subterms.  So in:
 544 **
 545 **     ... WHERE  (a=5) AND (b=7 OR c=9 OR d=13) AND (d=13)
 546 **                          ^^^^^^^^^^^^^^^^^^^^
 547 **
 548 ** This routine analyzes terms such as the middle term in the above example.
 549 ** A WhereOrTerm object is computed and attached to the term under
 550 ** analysis, regardless of the outcome of the analysis.  Hence:
 551 **
 552 **     WhereTerm.wtFlags   |=  TERM_ORINFO
 553 **     WhereTerm.u.pOrInfo  =  a dynamically allocated WhereOrTerm object
 554 **
 555 ** The term being analyzed must have two or more of OR-connected subterms.
 556 ** A single subterm might be a set of AND-connected sub-subterms.
 557 ** Examples of terms under analysis:
 558 **
 559 **     (A)     t1.x=t2.y OR t1.x=t2.z OR t1.y=15 OR t1.z=t3.a+5
 560 **     (B)     x=expr1 OR expr2=x OR x=expr3
 561 **     (C)     t1.x=t2.y OR (t1.x=t2.z AND t1.y=15)
 562 **     (D)     x=expr1 OR (y>11 AND y<22 AND z LIKE '*hello*')
 563 **     (E)     (p.a=1 AND q.b=2 AND r.c=3) OR (p.x=4 AND q.y=5 AND r.z=6)
 564 **     (F)     x>A OR (x=A AND y>=B)
 565 **
 566 ** CASE 1:
 567 **
 568 ** If all subterms are of the form T.C=expr for some single column of C and
 569 ** a single table T (as shown in example B above) then create a new virtual
 570 ** term that is an equivalent IN expression.  In other words, if the term
 571 ** being analyzed is:
 572 **
 573 **      x = expr1  OR  expr2 = x  OR  x = expr3
 574 **
 575 ** then create a new virtual term like this:
 576 **
 577 **      x IN (expr1,expr2,expr3)
 578 **
 579 ** CASE 2:
 580 **
 581 ** If there are exactly two disjuncts and one side has x>A and the other side
 582 ** has x=A (for the same x and A) then add a new virtual conjunct term to the
 583 ** WHERE clause of the form "x>=A".  Example:
 584 **
 585 **      x>A OR (x=A AND y>B)    adds:    x>=A
 586 **
 587 ** The added conjunct can sometimes be helpful in query planning.
 588 **
 589 ** CASE 3:
 590 **
 591 ** If all subterms are indexable by a single table T, then set
 592 **
 593 **     WhereTerm.eOperator              =  WO_OR
 594 **     WhereTerm.u.pOrInfo->indexable  |=  the cursor number for table T
 595 **
 596 ** A subterm is "indexable" if it is of the form
 597 ** "T.C <op> <expr>" where C is any column of table T and
 598 ** <op> is one of "=", "<", "<=", ">", ">=", "IS NULL", or "IN".
 599 ** A subterm is also indexable if it is an AND of two or more
 600 ** subsubterms at least one of which is indexable.  Indexable AND
 601 ** subterms have their eOperator set to WO_AND and they have
 602 ** u.pAndInfo set to a dynamically allocated WhereAndTerm object.
 603 **
 604 ** From another point of view, "indexable" means that the subterm could
 605 ** potentially be used with an index if an appropriate index exists.
 606 ** This analysis does not consider whether or not the index exists; that
 607 ** is decided elsewhere.  This analysis only looks at whether subterms
 608 ** appropriate for indexing exist.
 609 **
 610 ** All examples A through E above satisfy case 3.  But if a term
 611 ** also satisfies case 1 (such as B) we know that the optimizer will
 612 ** always prefer case 1, so in that case we pretend that case 3 is not
 613 ** satisfied.
 614 **
 615 ** It might be the case that multiple tables are indexable.  For example,
 616 ** (E) above is indexable on tables P, Q, and R.
 617 **
 618 ** Terms that satisfy case 3 are candidates for lookup by using
 619 ** separate indices to find rowids for each subterm and composing
 620 ** the union of all rowids using a RowSet object.  This is similar
 621 ** to "bitmap indices" in other database engines.
 622 **
 623 ** OTHERWISE:
 624 **
 625 ** If none of cases 1, 2, or 3 apply, then leave the eOperator set to
 626 ** zero.  This term is not useful for search.
 627 */
 628 static void exprAnalyzeOrTerm(
 629   SrcList *pSrc,            /* the FROM clause */
 630   WhereClause *pWC,         /* the complete WHERE clause */
 631   int idxTerm               /* Index of the OR-term to be analyzed */
 632 ){
 633   WhereInfo *pWInfo = pWC->pWInfo;        /* WHERE clause processing context */
 634   Parse *pParse = pWInfo->pParse;         /* Parser context */
 635   sqlite3 *db = pParse->db;               /* Database connection */
 636   WhereTerm *pTerm = &pWC->a[idxTerm];    /* The term to be analyzed */
 637   Expr *pExpr = pTerm->pExpr;             /* The expression of the term */
 638   int i;                                  /* Loop counters */
 639   WhereClause *pOrWc;       /* Breakup of pTerm into subterms */
 640   WhereTerm *pOrTerm;       /* A Sub-term within the pOrWc */
 641   WhereOrInfo *pOrInfo;     /* Additional information associated with pTerm */
 642   Bitmask chngToIN;         /* Tables that might satisfy case 1 */
 643   Bitmask indexable;        /* Tables that are indexable, satisfying case 2 */
 644
 645   /*
 646   ** Break the OR clause into its separate subterms.  The subterms are
 647   ** stored in a WhereClause structure containing within the WhereOrInfo
 648   ** object that is attached to the original OR clause term.
 649   */
 650   assert( (pTerm->wtFlags & (TERM_DYNAMIC|TERM_ORINFO|TERM_ANDINFO))==0 );
 651   assert( pExpr->op==TK_OR );
 652   pTerm->u.pOrInfo = pOrInfo = sqlite3DbMallocZero(db, sizeof(*pOrInfo));
 653   if( pOrInfo==0 ) return;
 654   pTerm->wtFlags |= TERM_ORINFO;
 655   pOrWc = &pOrInfo->wc;
 656   memset(pOrWc->aStatic, 0, sizeof(pOrWc->aStatic));
 657   sqlite3WhereClauseInit(pOrWc, pWInfo);
 658   sqlite3WhereSplit(pOrWc, pExpr, TK_OR);
 659   sqlite3WhereExprAnalyze(pSrc, pOrWc);
 660   if( db->mallocFailed ) return;
 661   assert( pOrWc->nTerm>=2 );
 662
 663   /*
 664   ** Compute the set of tables that might satisfy cases 1 or 3.
 665   */
 666   indexable = ~(Bitmask)0;
 667   chngToIN = ~(Bitmask)0;
 668   for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0 && indexable; i--, pOrTerm++){
 669     if( (pOrTerm->eOperator & WO_SINGLE)==0 ){
 670       WhereAndInfo *pAndInfo;
 671       assert( (pOrTerm->wtFlags & (TERM_ANDINFO|TERM_ORINFO))==0 );
 672       chngToIN = 0;
 673       pAndInfo = sqlite3DbMallocRawNN(db, sizeof(*pAndInfo));
 674       if( pAndInfo ){
 675         WhereClause *pAndWC;
 676         WhereTerm *pAndTerm;
 677         int j;
 678         Bitmask b = 0;
 679         pOrTerm->u.pAndInfo = pAndInfo;
 680         pOrTerm->wtFlags |= TERM_ANDINFO;
 681         pOrTerm->eOperator = WO_AND;
 682         pAndWC = &pAndInfo->wc;
 683         memset(pAndWC->aStatic, 0, sizeof(pAndWC->aStatic));
 684         sqlite3WhereClauseInit(pAndWC, pWC->pWInfo);
 685         sqlite3WhereSplit(pAndWC, pOrTerm->pExpr, TK_AND);
 686         sqlite3WhereExprAnalyze(pSrc, pAndWC);
 687         pAndWC->pOuter = pWC;
 688         if( !db->mallocFailed ){
 689           for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){
 690             assert( pAndTerm->pExpr );
 691             if( allowedOp(pAndTerm->pExpr->op)
 692              || pAndTerm->eOperator==WO_AUX
 693             ){
 694               b |= sqlite3WhereGetMask(&pWInfo->sMaskSet, pAndTerm->leftCursor);
 695             }
 696           }
 697         }
 698         indexable &= b;
 699       }
 700     }else if( pOrTerm->wtFlags & TERM_COPIED ){
 701       /* Skip this term for now.  We revisit it when we process the
 702       ** corresponding TERM_VIRTUAL term */
 703     }else{
 704       Bitmask b;
 705       b = sqlite3WhereGetMask(&pWInfo->sMaskSet, pOrTerm->leftCursor);
 706       if( pOrTerm->wtFlags & TERM_VIRTUAL ){
 707         WhereTerm *pOther = &pOrWc->a[pOrTerm->iParent];
 708         b |= sqlite3WhereGetMask(&pWInfo->sMaskSet, pOther->leftCursor);
 709       }
 710       indexable &= b;
 711       if( (pOrTerm->eOperator & WO_EQ)==0 ){
 712         chngToIN = 0;
 713       }else{
 714         chngToIN &= b;
 715       }
 716     }
 717   }
 718
 719   /*
 720   ** Record the set of tables that satisfy case 3.  The set might be
 721   ** empty.
 722   */
 723   pOrInfo->indexable = indexable;
 724   if( indexable ){
 725     pTerm->eOperator = WO_OR;
 726     pWC->hasOr = 1;
 727   }else{
 728     pTerm->eOperator = WO_OR;
 729   }
 730
 731   /* For a two-way OR, attempt to implementation case 2.
 732   */
 733   if( indexable && pOrWc->nTerm==2 ){
 734     int iOne = 0;
 735     WhereTerm *pOne;
 736     while( (pOne = whereNthSubterm(&pOrWc->a[0],iOne++))!=0 ){
 737       int iTwo = 0;
 738       WhereTerm *pTwo;
 739       while( (pTwo = whereNthSubterm(&pOrWc->a[1],iTwo++))!=0 ){
 740         whereCombineDisjuncts(pSrc, pWC, pOne, pTwo);
 741       }
 742     }
 743   }
 744
 745   /*
 746   ** chngToIN holds a set of tables that *might* satisfy case 1.  But
 747   ** we have to do some additional checking to see if case 1 really
 748   ** is satisfied.
 749   **
 750   ** chngToIN will hold either 0, 1, or 2 bits.  The 0-bit case means
 751   ** that there is no possibility of transforming the OR clause into an
 752   ** IN operator because one or more terms in the OR clause contain
 753   ** something other than == on a column in the single table.  The 1-bit
 754   ** case means that every term of the OR clause is of the form
 755   ** "table.column=expr" for some single table.  The one bit that is set
 756   ** will correspond to the common table.  We still need to check to make
 757   ** sure the same column is used on all terms.  The 2-bit case is when
 758   ** the all terms are of the form "table1.column=table2.column".  It
 759   ** might be possible to form an IN operator with either table1.column
 760   ** or table2.column as the LHS if either is common to every term of
 761   ** the OR clause.
 762   **
 763   ** Note that terms of the form "table.column1=table.column2" (the
 764   ** same table on both sizes of the ==) cannot be optimized.
 765   */
 766   if( chngToIN ){
 767     int okToChngToIN = 0;     /* True if the conversion to IN is valid */
 768     int iColumn = -1;         /* Column index on lhs of IN operator */
 769     int iCursor = -1;         /* Table cursor common to all terms */
 770     int j = 0;                /* Loop counter */
 771
 772     /* Search for a table and column that appears on one side or the
 773     ** other of the == operator in every subterm.  That table and column
 774     ** will be recorded in iCursor and iColumn.  There might not be any
 775     ** such table and column.  Set okToChngToIN if an appropriate table
 776     ** and column is found but leave okToChngToIN false if not found.
 777     */
 778     for(j=0; j<2 && !okToChngToIN; j++){
 779       Expr *pLeft = 0;
 780       pOrTerm = pOrWc->a;
 781       for(i=pOrWc->nTerm-1; i>=0; i--, pOrTerm++){
 782         assert( pOrTerm->eOperator & WO_EQ );
 783         pOrTerm->wtFlags &= ~TERM_OR_OK;
 784         if( pOrTerm->leftCursor==iCursor ){
 785           /* This is the 2-bit case and we are on the second iteration and
 786           ** current term is from the first iteration.  So skip this term. */
 787           assert( j==1 );
 788           continue;
 789         }
 790         if( (chngToIN & sqlite3WhereGetMask(&pWInfo->sMaskSet,
 791                                             pOrTerm->leftCursor))==0 ){
 792           /* This term must be of the form t1.a==t2.b where t2 is in the
 793           ** chngToIN set but t1 is not.  This term will be either preceded
 794           ** or follwed by an inverted copy (t2.b==t1.a).  Skip this term
 795           ** and use its inversion. */
 796           testcase( pOrTerm->wtFlags & TERM_COPIED );
 797           testcase( pOrTerm->wtFlags & TERM_VIRTUAL );
 798           assert( pOrTerm->wtFlags & (TERM_COPIED|TERM_VIRTUAL) );
 799           continue;
 800         }
 801         iColumn = pOrTerm->u.leftColumn;
 802         iCursor = pOrTerm->leftCursor;
 803         pLeft = pOrTerm->pExpr->pLeft;
 804         break;
 805       }
 806       if( i<0 ){
 807         /* No candidate table+column was found.  This can only occur
 808         ** on the second iteration */
 809         assert( j==1 );
 810         assert( IsPowerOfTwo(chngToIN) );
 811         assert( chngToIN==sqlite3WhereGetMask(&pWInfo->sMaskSet, iCursor) );
 812         break;
 813       }
 814       testcase( j==1 );
 815
 816       /* We have found a candidate table and column.  Check to see if that
 817       ** table and column is common to every term in the OR clause */
 818       okToChngToIN = 1;
 819       for(; i>=0 && okToChngToIN; i--, pOrTerm++){
 820         assert( pOrTerm->eOperator & WO_EQ );
 821         if( pOrTerm->leftCursor!=iCursor ){
 822           pOrTerm->wtFlags &= ~TERM_OR_OK;
 823         }else if( pOrTerm->u.leftColumn!=iColumn || (iColumn==XN_EXPR
 824                && sqlite3ExprCompare(pParse, pOrTerm->pExpr->pLeft, pLeft, -1)
 825         )){
 826           okToChngToIN = 0;
 827         }else{
 828           int affLeft, affRight;
 829           /* If the right-hand side is also a column, then the affinities
 830           ** of both right and left sides must be such that no type
 831           ** conversions are required on the right.  (Ticket #2249)
 832           */
 833           affRight = sqlite3ExprAffinity(pOrTerm->pExpr->pRight);
 834           affLeft = sqlite3ExprAffinity(pOrTerm->pExpr->pLeft);
 835           if( affRight!=0 && affRight!=affLeft ){
 836             okToChngToIN = 0;
 837           }else{
 838             pOrTerm->wtFlags |= TERM_OR_OK;
 839           }
 840         }
 841       }
 842     }
 843
 844     /* At this point, okToChngToIN is true if original pTerm satisfies
 845     ** case 1.  In that case, construct a new virtual term that is
 846     ** pTerm converted into an IN operator.
 847     */
 848     if( okToChngToIN ){
 849       Expr *pDup;            /* A transient duplicate expression */
 850       ExprList *pList = 0;   /* The RHS of the IN operator */
 851       Expr *pLeft = 0;       /* The LHS of the IN operator */
 852       Expr *pNew;            /* The complete IN operator */
 853
 854       for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0; i--, pOrTerm++){
 855         if( (pOrTerm->wtFlags & TERM_OR_OK)==0 ) continue;
 856         assert( pOrTerm->eOperator & WO_EQ );
 857         assert( pOrTerm->leftCursor==iCursor );
 858         assert( pOrTerm->u.leftColumn==iColumn );
 859         pDup = sqlite3ExprDup(db, pOrTerm->pExpr->pRight, 0);
 860         pList = sqlite3ExprListAppend(pWInfo->pParse, pList, pDup);
 861         pLeft = pOrTerm->pExpr->pLeft;
 862       }
 863       assert( pLeft!=0 );
 864       pDup = sqlite3ExprDup(db, pLeft, 0);
 865       pNew = sqlite3PExpr(pParse, TK_IN, pDup, 0);
 866       if( pNew ){
 867         int idxNew;
 868         transferJoinMarkings(pNew, pExpr);
 869         assert( !ExprHasProperty(pNew, EP_xIsSelect) );
 870         pNew->x.pList = pList;
 871         idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC);
 872         testcase( idxNew==0 );
 873         exprAnalyze(pSrc, pWC, idxNew);
 874         /* pTerm = &pWC->a[idxTerm]; // would be needed if pTerm where used again */
 875         markTermAsChild(pWC, idxNew, idxTerm);
 876       }else{
 877         sqlite3ExprListDelete(db, pList);
 878       }
 879     }
 880   }
 881 }
 882 #endif /* !SQLITE_OMIT_OR_OPTIMIZATION && !SQLITE_OMIT_SUBQUERY */
 883
 884 /*
 885 ** We already know that pExpr is a binary operator where both operands are
 886 ** column references.  This routine checks to see if pExpr is an equivalence
 887 ** relation:
 888 **   1.  The SQLITE_Transitive optimization must be enabled
 889 **   2.  Must be either an == or an IS operator
 890 **   3.  Not originating in the ON clause of an OUTER JOIN
 891 **   4.  The affinities of A and B must be compatible
 892 **   5a. Both operands use the same collating sequence OR
 893 **   5b. The overall collating sequence is BINARY
 894 ** If this routine returns TRUE, that means that the RHS can be substituted
 895 ** for the LHS anyplace else in the WHERE clause where the LHS column occurs.
 896 ** This is an optimization.  No harm comes from returning 0.  But if 1 is
 897 ** returned when it should not be, then incorrect answers might result.
 898 */
 899 static int termIsEquivalence(Parse *pParse, Expr *pExpr){
 900   char aff1, aff2;
 901   CollSeq *pColl;
 902   if( !OptimizationEnabled(pParse->db, SQLITE_Transitive) ) return 0;
 903   if( pExpr->op!=TK_EQ && pExpr->op!=TK_IS ) return 0;
 904   if( ExprHasProperty(pExpr, EP_FromJoin) ) return 0;
 905   aff1 = sqlite3ExprAffinity(pExpr->pLeft);
 906   aff2 = sqlite3ExprAffinity(pExpr->pRight);
 907   if( aff1!=aff2
 908    && (!sqlite3IsNumericAffinity(aff1) || !sqlite3IsNumericAffinity(aff2))
 909   ){
 910     return 0;
 911   }
 912   pColl = sqlite3ExprCompareCollSeq(pParse, pExpr);
 913   if( sqlite3IsBinary(pColl) ) return 1;
 914   return sqlite3ExprCollSeqMatch(pParse, pExpr->pLeft, pExpr->pRight);
 915 }
 916
 917 /*
 918 ** Recursively walk the expressions of a SELECT statement and generate
 919 ** a bitmask indicating which tables are used in that expression
 920 ** tree.
 921 */
 922 static Bitmask exprSelectUsage(WhereMaskSet *pMaskSet, Select *pS){
 923   Bitmask mask = 0;
 924   while( pS ){
 925     SrcList *pSrc = pS->pSrc;
 926     mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pEList);
 927     mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pGroupBy);
 928     mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pOrderBy);
 929     mask |= sqlite3WhereExprUsage(pMaskSet, pS->pWhere);
 930     mask |= sqlite3WhereExprUsage(pMaskSet, pS->pHaving);
 931     if( ALWAYS(pSrc!=0) ){
 932       int i;
 933       for(i=0; i<pSrc->nSrc; i++){
 934         mask |= exprSelectUsage(pMaskSet, pSrc->a[i].pSelect);
 935         mask |= sqlite3WhereExprUsage(pMaskSet, pSrc->a[i].pOn);
 936         if( pSrc->a[i].fg.isTabFunc ){
 937           mask |= sqlite3WhereExprListUsage(pMaskSet, pSrc->a[i].u1.pFuncArg);
 938         }
 939       }
 940     }
 941     pS = pS->pPrior;
 942   }
 943   return mask;
 944 }
 945
 946 /*
 947 ** Expression pExpr is one operand of a comparison operator that might
 948 ** be useful for indexing.  This routine checks to see if pExpr appears
 949 ** in any index.  Return TRUE (1) if pExpr is an indexed term and return
 950 ** FALSE (0) if not.  If TRUE is returned, also set aiCurCol[0] to the cursor
 951 ** number of the table that is indexed and aiCurCol[1] to the column number
 952 ** of the column that is indexed, or XN_EXPR (-2) if an expression is being
 953 ** indexed.
 954 **
 955 ** If pExpr is a TK_COLUMN column reference, then this routine always returns
 956 ** true even if that particular column is not indexed, because the column
 957 ** might be added to an automatic index later.
 958 */
 959 static SQLITE_NOINLINE int exprMightBeIndexed2(
 960   SrcList *pFrom,        /* The FROM clause */
 961   Bitmask mPrereq,       /* Bitmask of FROM clause terms referenced by pExpr */
 962   int *aiCurCol,         /* Write the referenced table cursor and column here */
 963   Expr *pExpr            /* An operand of a comparison operator */
 964 ){
 965   Index *pIdx;
 966   int i;
 967   int iCur;
 968   for(i=0; mPrereq>1; i++, mPrereq>>=1){}
 969   iCur = pFrom->a[i].iCursor;
 970   for(pIdx=pFrom->a[i].pTab->pIndex; pIdx; pIdx=pIdx->pNext){
 971     if( pIdx->aColExpr==0 ) continue;
 972     for(i=0; i<pIdx->nKeyCol; i++){
 973       if( pIdx->aiColumn[i]!=XN_EXPR ) continue;
 974       if( sqlite3ExprCompareSkip(pExpr, pIdx->aColExpr->a[i].pExpr, iCur)==0 ){
 975         aiCurCol[0] = iCur;
 976         aiCurCol[1] = XN_EXPR;
 977         return 1;
 978       }
 979     }
 980   }
 981   return 0;
 982 }
 983 static int exprMightBeIndexed(
 984   SrcList *pFrom,        /* The FROM clause */
 985   Bitmask mPrereq,       /* Bitmask of FROM clause terms referenced by pExpr */
 986   int *aiCurCol,         /* Write the referenced table cursor & column here */
 987   Expr *pExpr,           /* An operand of a comparison operator */
 988   int op                 /* The specific comparison operator */
 989 ){
 990   /* If this expression is a vector to the left or right of a
 991   ** inequality constraint (>, <, >= or <=), perform the processing
 992   ** on the first element of the vector.  */
 993   assert( TK_GT+1==TK_LE && TK_GT+2==TK_LT && TK_GT+3==TK_GE );
 994   assert( TK_IS<TK_GE && TK_ISNULL<TK_GE && TK_IN<TK_GE );
 995   assert( op<=TK_GE );
 996   if( pExpr->op==TK_VECTOR && (op>=TK_GT && ALWAYS(op<=TK_GE)) ){
 997     pExpr = pExpr->x.pList->a[0].pExpr;
 998   }
 999
1000   if( pExpr->op==TK_COLUMN ){
1001     aiCurCol[0] = pExpr->iTable;
1002     aiCurCol[1] = pExpr->iColumn;
1003     return 1;
1004   }
1005   if( mPrereq==0 ) return 0;                 /* No table references */
1006   if( (mPrereq&(mPrereq-1))!=0 ) return 0;   /* Refs more than one table */
1007   return exprMightBeIndexed2(pFrom,mPrereq,aiCurCol,pExpr);
1008 }
1009
1010 /*
1011 ** The input to this routine is an WhereTerm structure with only the
1012 ** "pExpr" field filled in.  The job of this routine is to analyze the
1013 ** subexpression and populate all the other fields of the WhereTerm
1014 ** structure.
1015 **
1016 ** If the expression is of the form "<expr> <op> X" it gets commuted
1017 ** to the standard form of "X <op> <expr>".
1018 **
1019 ** If the expression is of the form "X <op> Y" where both X and Y are
1020 ** columns, then the original expression is unchanged and a new virtual
1021 ** term of the form "Y <op> X" is added to the WHERE clause and
1022 ** analyzed separately.  The original term is marked with TERM_COPIED
1023 ** and the new term is marked with TERM_DYNAMIC (because it's pExpr
1024 ** needs to be freed with the WhereClause) and TERM_VIRTUAL (because it
1025 ** is a commuted copy of a prior term.)  The original term has nChild=1
1026 ** and the copy has idxParent set to the index of the original term.
1027 */
1028 static void exprAnalyze(
1029   SrcList *pSrc,            /* the FROM clause */
1030   WhereClause *pWC,         /* the WHERE clause */
1031   int idxTerm               /* Index of the term to be analyzed */
1032 ){
1033   WhereInfo *pWInfo = pWC->pWInfo; /* WHERE clause processing context */
1034   WhereTerm *pTerm;                /* The term to be analyzed */
1035   WhereMaskSet *pMaskSet;          /* Set of table index masks */
1036   Expr *pExpr;                     /* The expression to be analyzed */
1037   Bitmask prereqLeft;              /* Prerequesites of the pExpr->pLeft */
1038   Bitmask prereqAll;               /* Prerequesites of pExpr */
1039   Bitmask extraRight = 0;          /* Extra dependencies on LEFT JOIN */
1040   Expr *pStr1 = 0;                 /* RHS of LIKE/GLOB operator */
1041   int isComplete = 0;              /* RHS of LIKE/GLOB ends with wildcard */
1042   int noCase = 0;                  /* uppercase equivalent to lowercase */
1043   int op;                          /* Top-level operator.  pExpr->op */
1044   Parse *pParse = pWInfo->pParse;  /* Parsing context */
1045   sqlite3 *db = pParse->db;        /* Database connection */
1046   unsigned char eOp2 = 0;          /* op2 value for LIKE/REGEXP/GLOB */
1047   int nLeft;                       /* Number of elements on left side vector */
1048
1049   if( db->mallocFailed ){
1050     return;
1051   }
1052   pTerm = &pWC->a[idxTerm];
1053   pMaskSet = &pWInfo->sMaskSet;
1054   pExpr = pTerm->pExpr;
1055   assert( pExpr->op!=TK_AS && pExpr->op!=TK_COLLATE );
1056   prereqLeft = sqlite3WhereExprUsage(pMaskSet, pExpr->pLeft);
1057   op = pExpr->op;
1058   if( op==TK_IN ){
1059     assert( pExpr->pRight==0 );
1060     if( sqlite3ExprCheckIN(pParse, pExpr) ) return;
1061     if( ExprHasProperty(pExpr, EP_xIsSelect) ){
1062       pTerm->prereqRight = exprSelectUsage(pMaskSet, pExpr->x.pSelect);
1063     }else{
1064       pTerm->prereqRight = sqlite3WhereExprListUsage(pMaskSet, pExpr->x.pList);
1065     }
1066   }else if( op==TK_ISNULL ){
1067     pTerm->prereqRight = 0;
1068   }else{
1069     pTerm->prereqRight = sqlite3WhereExprUsage(pMaskSet, pExpr->pRight);
1070   }
1071   pMaskSet->bVarSelect = 0;
1072   prereqAll = sqlite3WhereExprUsageNN(pMaskSet, pExpr);
1073   if( pMaskSet->bVarSelect ) pTerm->wtFlags |= TERM_VARSELECT;
1074   if( ExprHasProperty(pExpr, EP_FromJoin) ){
1075     Bitmask x = sqlite3WhereGetMask(pMaskSet, pExpr->iRightJoinTable);
1076     prereqAll |= x;
1077     extraRight = x-1;  /* ON clause terms may not be used with an index
1078                        ** on left table of a LEFT JOIN.  Ticket #3015 */
1079     if( (prereqAll>>1)>=x ){
1080       sqlite3ErrorMsg(pParse, "ON clause references tables to its right");
1081       return;
1082     }
1083   }
1084   pTerm->prereqAll = prereqAll;
1085   pTerm->leftCursor = -1;
1086   pTerm->iParent = -1;
1087   pTerm->eOperator = 0;
1088   if( allowedOp(op) ){
1089     int aiCurCol[2];
1090     Expr *pLeft = sqlite3ExprSkipCollate(pExpr->pLeft);
1091     Expr *pRight = sqlite3ExprSkipCollate(pExpr->pRight);
1092     u16 opMask = (pTerm->prereqRight & prereqLeft)==0 ? WO_ALL : WO_EQUIV;
1093
1094     if( pTerm->iField>0 ){
1095       assert( op==TK_IN );
1096       assert( pLeft->op==TK_VECTOR );
1097       pLeft = pLeft->x.pList->a[pTerm->iField-1].pExpr;
1098     }
1099
1100     if( exprMightBeIndexed(pSrc, prereqLeft, aiCurCol, pLeft, op) ){
1101       pTerm->leftCursor = aiCurCol[0];
1102       pTerm->u.leftColumn = aiCurCol[1];
1103       pTerm->eOperator = operatorMask(op) & opMask;
1104     }
1105     if( op==TK_IS ) pTerm->wtFlags |= TERM_IS;
1106     if( pRight
1107      && exprMightBeIndexed(pSrc, pTerm->prereqRight, aiCurCol, pRight, op)
1108     ){
1109       WhereTerm *pNew;
1110       Expr *pDup;
1111       u16 eExtraOp = 0;        /* Extra bits for pNew->eOperator */
1112       assert( pTerm->iField==0 );
1113       if( pTerm->leftCursor>=0 ){
1114         int idxNew;
1115         pDup = sqlite3ExprDup(db, pExpr, 0);
1116         if( db->mallocFailed ){
1117           sqlite3ExprDelete(db, pDup);
1118           return;
1119         }
1120         idxNew = whereClauseInsert(pWC, pDup, TERM_VIRTUAL|TERM_DYNAMIC);
1121         if( idxNew==0 ) return;
1122         pNew = &pWC->a[idxNew];
1123         markTermAsChild(pWC, idxNew, idxTerm);
1124         if( op==TK_IS ) pNew->wtFlags |= TERM_IS;
1125         pTerm = &pWC->a[idxTerm];
1126         pTerm->wtFlags |= TERM_COPIED;
1127
1128         if( termIsEquivalence(pParse, pDup) ){
1129           pTerm->eOperator |= WO_EQUIV;
1130           eExtraOp = WO_EQUIV;
1131         }
1132       }else{
1133         pDup = pExpr;
1134         pNew = pTerm;
1135       }
1136       pNew->wtFlags |= exprCommute(pParse, pDup);
1137       pNew->leftCursor = aiCurCol[0];
1138       pNew->u.leftColumn = aiCurCol[1];
1139       testcase( (prereqLeft | extraRight) != prereqLeft );
1140       pNew->prereqRight = prereqLeft | extraRight;
1141       pNew->prereqAll = prereqAll;
1142       pNew->eOperator = (operatorMask(pDup->op) + eExtraOp) & opMask;
1143     }
1144   }
1145
1146 #ifndef SQLITE_OMIT_BETWEEN_OPTIMIZATION
1147   /* If a term is the BETWEEN operator, create two new virtual terms
1148   ** that define the range that the BETWEEN implements.  For example:
1149   **
1150   **      a BETWEEN b AND c
1151   **
1152   ** is converted into:
1153   **
1154   **      (a BETWEEN b AND c) AND (a>=b) AND (a<=c)
1155   **
1156   ** The two new terms are added onto the end of the WhereClause object.
1157   ** The new terms are "dynamic" and are children of the original BETWEEN
1158   ** term.  That means that if the BETWEEN term is coded, the children are
1159   ** skipped.  Or, if the children are satisfied by an index, the original
1160   ** BETWEEN term is skipped.
1161   */
1162   else if( pExpr->op==TK_BETWEEN && pWC->op==TK_AND ){
1163     ExprList *pList = pExpr->x.pList;
1164     int i;
1165     static const u8 ops[] = {TK_GE, TK_LE};
1166     assert( pList!=0 );
1167     assert( pList->nExpr==2 );
1168     for(i=0; i<2; i++){
1169       Expr *pNewExpr;
1170       int idxNew;
1171       pNewExpr = sqlite3PExpr(pParse, ops[i],
1172                              sqlite3ExprDup(db, pExpr->pLeft, 0),
1173                              sqlite3ExprDup(db, pList->a[i].pExpr, 0));
1174       transferJoinMarkings(pNewExpr, pExpr);
1175       idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
1176       testcase( idxNew==0 );
1177       exprAnalyze(pSrc, pWC, idxNew);
1178       pTerm = &pWC->a[idxTerm];
1179       markTermAsChild(pWC, idxNew, idxTerm);
1180     }
1181   }
1182 #endif /* SQLITE_OMIT_BETWEEN_OPTIMIZATION */
1183
1184 #if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
1185   /* Analyze a term that is composed of two or more subterms connected by
1186   ** an OR operator.
1187   */
1188   else if( pExpr->op==TK_OR ){
1189     assert( pWC->op==TK_AND );
1190     exprAnalyzeOrTerm(pSrc, pWC, idxTerm);
1191     pTerm = &pWC->a[idxTerm];
1192   }
1193 #endif /* SQLITE_OMIT_OR_OPTIMIZATION */
1194
1195 #ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
1196   /* Add constraints to reduce the search space on a LIKE or GLOB
1197   ** operator.
1198   **
1199   ** A like pattern of the form "x LIKE 'aBc%'" is changed into constraints
1200   **
1201   **          x>='ABC' AND x<'abd' AND x LIKE 'aBc%'
1202   **
1203   ** The last character of the prefix "abc" is incremented to form the
1204   ** termination condition "abd".  If case is not significant (the default
1205   ** for LIKE) then the lower-bound is made all uppercase and the upper-
1206   ** bound is made all lowercase so that the bounds also work when comparing
1207   ** BLOBs.
1208   */
1209   if( pWC->op==TK_AND
1210    && isLikeOrGlob(pParse, pExpr, &pStr1, &isComplete, &noCase)
1211   ){
1212     Expr *pLeft;       /* LHS of LIKE/GLOB operator */
1213     Expr *pStr2;       /* Copy of pStr1 - RHS of LIKE/GLOB operator */
1214     Expr *pNewExpr1;
1215     Expr *pNewExpr2;
1216     int idxNew1;
1217     int idxNew2;
1218     const char *zCollSeqName;     /* Name of collating sequence */
1219     const u16 wtFlags = TERM_LIKEOPT | TERM_VIRTUAL | TERM_DYNAMIC;
1220
1221     pLeft = pExpr->x.pList->a[1].pExpr;
1222     pStr2 = sqlite3ExprDup(db, pStr1, 0);
1223
1224     /* Convert the lower bound to upper-case and the upper bound to
1225     ** lower-case (upper-case is less than lower-case in ASCII) so that
1226     ** the range constraints also work for BLOBs
1227     */
1228     if( noCase && !pParse->db->mallocFailed ){
1229       int i;
1230       char c;
1231       pTerm->wtFlags |= TERM_LIKE;
1232       for(i=0; (c = pStr1->u.zToken[i])!=0; i++){
1233         pStr1->u.zToken[i] = sqlite3Toupper(c);
1234         pStr2->u.zToken[i] = sqlite3Tolower(c);
1235       }
1236     }
1237
1238     if( !db->mallocFailed ){
1239       u8 c, *pC;       /* Last character before the first wildcard */
1240       pC = (u8*)&pStr2->u.zToken[sqlite3Strlen30(pStr2->u.zToken)-1];
1241       c = *pC;
1242       if( noCase ){
1243         /* The point is to increment the last character before the first
1244         ** wildcard.  But if we increment '@', that will push it into the
1245         ** alphabetic range where case conversions will mess up the
1246         ** inequality.  To avoid this, make sure to also run the full
1247         ** LIKE on all candidate expressions by clearing the isComplete flag
1248         */
1249         if( c=='A'-1 ) isComplete = 0;
1250         c = sqlite3UpperToLower[c];
1251       }
1252       *pC = c + 1;
1253     }
1254     zCollSeqName = noCase ? "NOCASE" : sqlite3StrBINARY;
1255     pNewExpr1 = sqlite3ExprDup(db, pLeft, 0);
1256     pNewExpr1 = sqlite3PExpr(pParse, TK_GE,
1257            sqlite3ExprAddCollateString(pParse,pNewExpr1,zCollSeqName),
1258            pStr1);
1259     transferJoinMarkings(pNewExpr1, pExpr);
1260     idxNew1 = whereClauseInsert(pWC, pNewExpr1, wtFlags);
1261     testcase( idxNew1==0 );
1262     exprAnalyze(pSrc, pWC, idxNew1);
1263     pNewExpr2 = sqlite3ExprDup(db, pLeft, 0);
1264     pNewExpr2 = sqlite3PExpr(pParse, TK_LT,
1265            sqlite3ExprAddCollateString(pParse,pNewExpr2,zCollSeqName),
1266            pStr2);
1267     transferJoinMarkings(pNewExpr2, pExpr);
1268     idxNew2 = whereClauseInsert(pWC, pNewExpr2, wtFlags);
1269     testcase( idxNew2==0 );
1270     exprAnalyze(pSrc, pWC, idxNew2);
1271     pTerm = &pWC->a[idxTerm];
1272     if( isComplete ){
1273       markTermAsChild(pWC, idxNew1, idxTerm);
1274       markTermAsChild(pWC, idxNew2, idxTerm);
1275     }
1276   }
1277 #endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
1278
1279 #ifndef SQLITE_OMIT_VIRTUALTABLE
1280   /* Add a WO_AUX auxiliary term to the constraint set if the
1281   ** current expression is of the form "column OP expr" where OP
1282   ** is an operator that gets passed into virtual tables but which is
1283   ** not normally optimized for ordinary tables.  In other words, OP
1284   ** is one of MATCH, LIKE, GLOB, REGEXP, !=, IS, IS NOT, or NOT NULL.
1285   ** This information is used by the xBestIndex methods of
1286   ** virtual tables.  The native query optimizer does not attempt
1287   ** to do anything with MATCH functions.
1288   */
1289   if( pWC->op==TK_AND ){
1290     Expr *pRight = 0, *pLeft = 0;
1291     int res = isAuxiliaryVtabOperator(db, pExpr, &eOp2, &pLeft, &pRight);
1292     while( res-- > 0 ){
1293       int idxNew;
1294       WhereTerm *pNewTerm;
1295       Bitmask prereqColumn, prereqExpr;
1296
1297       prereqExpr = sqlite3WhereExprUsage(pMaskSet, pRight);
1298       prereqColumn = sqlite3WhereExprUsage(pMaskSet, pLeft);
1299       if( (prereqExpr & prereqColumn)==0 ){
1300         Expr *pNewExpr;
1301         pNewExpr = sqlite3PExpr(pParse, TK_MATCH,
1302             0, sqlite3ExprDup(db, pRight, 0));
1303         if( ExprHasProperty(pExpr, EP_FromJoin) && pNewExpr ){
1304           ExprSetProperty(pNewExpr, EP_FromJoin);
1305           pNewExpr->iRightJoinTable = pExpr->iRightJoinTable;
1306         }
1307         idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
1308         testcase( idxNew==0 );
1309         pNewTerm = &pWC->a[idxNew];
1310         pNewTerm->prereqRight = prereqExpr;
1311         pNewTerm->leftCursor = pLeft->iTable;
1312         pNewTerm->u.leftColumn = pLeft->iColumn;
1313         pNewTerm->eOperator = WO_AUX;
1314         pNewTerm->eMatchOp = eOp2;
1315         markTermAsChild(pWC, idxNew, idxTerm);
1316         pTerm = &pWC->a[idxTerm];
1317         pTerm->wtFlags |= TERM_COPIED;
1318         pNewTerm->prereqAll = pTerm->prereqAll;
1319       }
1320       SWAP(Expr*, pLeft, pRight);
1321     }
1322   }
1323 #endif /* SQLITE_OMIT_VIRTUALTABLE */
1324
1325   /* If there is a vector == or IS term - e.g. "(a, b) == (?, ?)" - create
1326   ** new terms for each component comparison - "a = ?" and "b = ?".  The
1327   ** new terms completely replace the original vector comparison, which is
1328   ** no longer used.
1329   **
1330   ** This is only required if at least one side of the comparison operation
1331   ** is not a sub-select.  */
1332   if( pWC->op==TK_AND
1333   && (pExpr->op==TK_EQ || pExpr->op==TK_IS)
1334   && (nLeft = sqlite3ExprVectorSize(pExpr->pLeft))>1
1335   && sqlite3ExprVectorSize(pExpr->pRight)==nLeft
1336   && ( (pExpr->pLeft->flags & EP_xIsSelect)==0
1337     || (pExpr->pRight->flags & EP_xIsSelect)==0)
1338   ){
1339     int i;
1340     for(i=0; i<nLeft; i++){
1341       int idxNew;
1342       Expr *pNew;
1343       Expr *pLeft = sqlite3ExprForVectorField(pParse, pExpr->pLeft, i);
1344       Expr *pRight = sqlite3ExprForVectorField(pParse, pExpr->pRight, i);
1345
1346       pNew = sqlite3PExpr(pParse, pExpr->op, pLeft, pRight);
1347       transferJoinMarkings(pNew, pExpr);
1348       idxNew = whereClauseInsert(pWC, pNew, TERM_DYNAMIC);
1349       exprAnalyze(pSrc, pWC, idxNew);
1350     }
1351     pTerm = &pWC->a[idxTerm];
1352     pTerm->wtFlags |= TERM_CODED|TERM_VIRTUAL;  /* Disable the original */
1353     pTerm->eOperator = 0;
1354   }
1355
1356   /* If there is a vector IN term - e.g. "(a, b) IN (SELECT ...)" - create
1357   ** a virtual term for each vector component. The expression object
1358   ** used by each such virtual term is pExpr (the full vector IN(...)
1359   ** expression). The WhereTerm.iField variable identifies the index within
1360   ** the vector on the LHS that the virtual term represents.
1361   **
1362   ** This only works if the RHS is a simple SELECT (not a compound) that does
1363   ** not use window functions.
1364   */
1365   if( pWC->op==TK_AND && pExpr->op==TK_IN && pTerm->iField==0
1366    && pExpr->pLeft->op==TK_VECTOR
1367    && pExpr->x.pSelect->pPrior==0
1368 #ifndef SQLITE_OMIT_WINDOWFUNC
1369    && pExpr->x.pSelect->pWin==0
1370 #endif
1371   ){
1372     int i;
1373     for(i=0; i<sqlite3ExprVectorSize(pExpr->pLeft); i++){
1374       int idxNew;
1375       idxNew = whereClauseInsert(pWC, pExpr, TERM_VIRTUAL);
1376       pWC->a[idxNew].iField = i+1;
1377       exprAnalyze(pSrc, pWC, idxNew);
1378       markTermAsChild(pWC, idxNew, idxTerm);
1379     }
1380   }
1381
1382 #ifdef SQLITE_ENABLE_STAT4
1383   /* When sqlite_stat4 histogram data is available an operator of the
1384   ** form "x IS NOT NULL" can sometimes be evaluated more efficiently
1385   ** as "x>NULL" if x is not an INTEGER PRIMARY KEY.  So construct a
1386   ** virtual term of that form.
1387   **
1388   ** Note that the virtual term must be tagged with TERM_VNULL.
1389   */
1390   if( pExpr->op==TK_NOTNULL
1391    && pExpr->pLeft->op==TK_COLUMN
1392    && pExpr->pLeft->iColumn>=0
1393    && !ExprHasProperty(pExpr, EP_FromJoin)
1394    && OptimizationEnabled(db, SQLITE_Stat4)
1395   ){
1396     Expr *pNewExpr;
1397     Expr *pLeft = pExpr->pLeft;
1398     int idxNew;
1399     WhereTerm *pNewTerm;
1400
1401     pNewExpr = sqlite3PExpr(pParse, TK_GT,
1402                             sqlite3ExprDup(db, pLeft, 0),
1403                             sqlite3ExprAlloc(db, TK_NULL, 0, 0));
1404
1405     idxNew = whereClauseInsert(pWC, pNewExpr,
1406                               TERM_VIRTUAL|TERM_DYNAMIC|TERM_VNULL);
1407     if( idxNew ){
1408       pNewTerm = &pWC->a[idxNew];
1409       pNewTerm->prereqRight = 0;
1410       pNewTerm->leftCursor = pLeft->iTable;
1411       pNewTerm->u.leftColumn = pLeft->iColumn;
1412       pNewTerm->eOperator = WO_GT;
1413       markTermAsChild(pWC, idxNew, idxTerm);
1414       pTerm = &pWC->a[idxTerm];
1415       pTerm->wtFlags |= TERM_COPIED;
1416       pNewTerm->prereqAll = pTerm->prereqAll;
1417     }
1418   }
1419 #endif /* SQLITE_ENABLE_STAT4 */
1420
1421   /* Prevent ON clause terms of a LEFT JOIN from being used to drive
1422   ** an index for tables to the left of the join.
1423   */
1424   testcase( pTerm!=&pWC->a[idxTerm] );
1425   pTerm = &pWC->a[idxTerm];
1426   pTerm->prereqRight |= extraRight;
1427 }
1428
1429 /***************************************************************************
1430 ** Routines with file scope above.  Interface to the rest of the where.c
1431 ** subsystem follows.
1432 ***************************************************************************/
1433
1434 /*
1435 ** This routine identifies subexpressions in the WHERE clause where
1436 ** each subexpression is separated by the AND operator or some other
1437 ** operator specified in the op parameter.  The WhereClause structure
1438 ** is filled with pointers to subexpressions.  For example:
1439 **
1440 **    WHERE  a=='hello' AND coalesce(b,11)<10 AND (c+12!=d OR c==22)
1441 **           \________/     \_______________/     \________________/
1442 **            slot[0]            slot[1]               slot[2]
1443 **
1444 ** The original WHERE clause in pExpr is unaltered.  All this routine
1445 ** does is make slot[] entries point to substructure within pExpr.
1446 **
1447 ** In the previous sentence and in the diagram, "slot[]" refers to
1448 ** the WhereClause.a[] array.  The slot[] array grows as needed to contain
1449 ** all terms of the WHERE clause.
1450 */
1451 void sqlite3WhereSplit(WhereClause *pWC, Expr *pExpr, u8 op){
1452   Expr *pE2 = sqlite3ExprSkipCollateAndLikely(pExpr);
1453   pWC->op = op;
1454   if( pE2==0 ) return;
1455   if( pE2->op!=op ){
1456     whereClauseInsert(pWC, pExpr, 0);
1457   }else{
1458     sqlite3WhereSplit(pWC, pE2->pLeft, op);
1459     sqlite3WhereSplit(pWC, pE2->pRight, op);
1460   }
1461 }
1462
1463 /*
1464 ** Initialize a preallocated WhereClause structure.
1465 */
1466 void sqlite3WhereClauseInit(
1467   WhereClause *pWC,        /* The WhereClause to be initialized */
1468   WhereInfo *pWInfo        /* The WHERE processing context */
1469 ){
1470   pWC->pWInfo = pWInfo;
1471   pWC->hasOr = 0;
1472   pWC->pOuter = 0;
1473   pWC->nTerm = 0;
1474   pWC->nSlot = ArraySize(pWC->aStatic);
1475   pWC->a = pWC->aStatic;
1476 }
1477
1478 /*
1479 ** Deallocate a WhereClause structure.  The WhereClause structure
1480 ** itself is not freed.  This routine is the inverse of
1481 ** sqlite3WhereClauseInit().
1482 */
1483 void sqlite3WhereClauseClear(WhereClause *pWC){
1484   int i;
1485   WhereTerm *a;
1486   sqlite3 *db = pWC->pWInfo->pParse->db;
1487   for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){
1488     if( a->wtFlags & TERM_DYNAMIC ){
1489       sqlite3ExprDelete(db, a->pExpr);
1490     }
1491     if( a->wtFlags & TERM_ORINFO ){
1492       whereOrInfoDelete(db, a->u.pOrInfo);
1493     }else if( a->wtFlags & TERM_ANDINFO ){
1494       whereAndInfoDelete(db, a->u.pAndInfo);
1495     }
1496   }
1497   if( pWC->a!=pWC->aStatic ){
1498     sqlite3DbFree(db, pWC->a);
1499   }
1500 }
1501
1502
1503 /*
1504 ** These routines walk (recursively) an expression tree and generate
1505 ** a bitmask indicating which tables are used in that expression
1506 ** tree.
1507 */
1508 Bitmask sqlite3WhereExprUsageNN(WhereMaskSet *pMaskSet, Expr *p){
1509   Bitmask mask;
1510   if( p->op==TK_COLUMN && !ExprHasProperty(p, EP_FixedCol) ){
1511     return sqlite3WhereGetMask(pMaskSet, p->iTable);
1512   }else if( ExprHasProperty(p, EP_TokenOnly|EP_Leaf) ){
1513     assert( p->op!=TK_IF_NULL_ROW );
1514     return 0;
1515   }
1516   mask = (p->op==TK_IF_NULL_ROW) ? sqlite3WhereGetMask(pMaskSet, p->iTable) : 0;
1517   if( p->pLeft ) mask |= sqlite3WhereExprUsageNN(pMaskSet, p->pLeft);
1518   if( p->pRight ){
1519     mask |= sqlite3WhereExprUsageNN(pMaskSet, p->pRight);
1520     assert( p->x.pList==0 );
1521   }else if( ExprHasProperty(p, EP_xIsSelect) ){
1522     if( ExprHasProperty(p, EP_VarSelect) ) pMaskSet->bVarSelect = 1;
1523     mask |= exprSelectUsage(pMaskSet, p->x.pSelect);
1524   }else if( p->x.pList ){
1525     mask |= sqlite3WhereExprListUsage(pMaskSet, p->x.pList);
1526   }
1527 #ifndef SQLITE_OMIT_WINDOWFUNC
1528   if( (p->op==TK_FUNCTION || p->op==TK_AGG_FUNCTION) && p->y.pWin ){
1529     mask |= sqlite3WhereExprListUsage(pMaskSet, p->y.pWin->pPartition);
1530     mask |= sqlite3WhereExprListUsage(pMaskSet, p->y.pWin->pOrderBy);
1531     mask |= sqlite3WhereExprUsage(pMaskSet, p->y.pWin->pFilter);
1532   }
1533 #endif
1534   return mask;
1535 }
1536 Bitmask sqlite3WhereExprUsage(WhereMaskSet *pMaskSet, Expr *p){
1537   return p ? sqlite3WhereExprUsageNN(pMaskSet,p) : 0;
1538 }
1539 Bitmask sqlite3WhereExprListUsage(WhereMaskSet *pMaskSet, ExprList *pList){
1540   int i;
1541   Bitmask mask = 0;
1542   if( pList ){
1543     for(i=0; i<pList->nExpr; i++){
1544       mask |= sqlite3WhereExprUsage(pMaskSet, pList->a[i].pExpr);
1545     }
1546   }
1547   return mask;
1548 }
1549
1550
1551 /*
1552 ** Call exprAnalyze on all terms in a WHERE clause.
1553 **
1554 ** Note that exprAnalyze() might add new virtual terms onto the
1555 ** end of the WHERE clause.  We do not want to analyze these new
1556 ** virtual terms, so start analyzing at the end and work forward
1557 ** so that the added virtual terms are never processed.
1558 */
1559 void sqlite3WhereExprAnalyze(
1560   SrcList *pTabList,       /* the FROM clause */
1561   WhereClause *pWC         /* the WHERE clause to be analyzed */
1562 ){
1563   int i;
1564   for(i=pWC->nTerm-1; i>=0; i--){
1565     exprAnalyze(pTabList, pWC, i);
1566   }
1567 }
1568
1569 /*
1570 ** For table-valued-functions, transform the function arguments into
1571 ** new WHERE clause terms.
1572 **
1573 ** Each function argument translates into an equality constraint against
1574 ** a HIDDEN column in the table.
1575 */
1576 void sqlite3WhereTabFuncArgs(
1577   Parse *pParse,                    /* Parsing context */
1578   struct SrcList_item *pItem,       /* The FROM clause term to process */
1579   WhereClause *pWC                  /* Xfer function arguments to here */
1580 ){
1581   Table *pTab;
1582   int j, k;
1583   ExprList *pArgs;
1584   Expr *pColRef;
1585   Expr *pTerm;
1586   if( pItem->fg.isTabFunc==0 ) return;
1587   pTab = pItem->pTab;
1588   assert( pTab!=0 );
1589   pArgs = pItem->u1.pFuncArg;
1590   if( pArgs==0 ) return;
1591   for(j=k=0; j<pArgs->nExpr; j++){
1592     Expr *pRhs;
1593     while( k<pTab->nCol && (pTab->aCol[k].colFlags & COLFLAG_HIDDEN)==0 ){k++;}
1594     if( k>=pTab->nCol ){
1595       sqlite3ErrorMsg(pParse, "too many arguments on %s() - max %d",
1596                       pTab->zName, j);
1597       return;
1598     }
1599     pColRef = sqlite3ExprAlloc(pParse->db, TK_COLUMN, 0, 0);
1600     if( pColRef==0 ) return;
1601     pColRef->iTable = pItem->iCursor;
1602     pColRef->iColumn = k++;
1603     pColRef->y.pTab = pTab;
1604     pRhs = sqlite3PExpr(pParse, TK_UPLUS,
1605         sqlite3ExprDup(pParse->db, pArgs->a[j].pExpr, 0), 0);
1606     pTerm = sqlite3PExpr(pParse, TK_EQ, pColRef, pRhs);
1607     if( pItem->fg.jointype & JT_LEFT ){
1608       sqlite3SetJoinExpr(pTerm, pItem->iCursor);
1609     }
1610     whereClauseInsert(pWC, pTerm, TERM_DYNAMIC);
1611   }
1612 }