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 = sqlite3ExprSkipCollate(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 ** If left/right precedence rules come into play when determining the
 114 ** collating sequence, then COLLATE operators are adjusted to ensure
 115 ** that the collating sequence does not change.  For example:
 116 ** "Y collate NOCASE op X" becomes "X op Y" because any collation sequence on
 117 ** the left hand side of a comparison overrides any collation sequence
 118 ** attached to the right. For the same reason the EP_Collate flag
 119 ** is not commuted.
 120 */
 121 static void exprCommute(Parse *pParse, Expr *pExpr){
 122   u16 expRight = (pExpr->pRight->flags & EP_Collate);
 123   u16 expLeft = (pExpr->pLeft->flags & EP_Collate);
 124   assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN );
 125   if( expRight==expLeft ){
 126     /* Either X and Y both have COLLATE operator or neither do */
 127     if( expRight ){
 128       /* Both X and Y have COLLATE operators.  Make sure X is always
 129       ** used by clearing the EP_Collate flag from Y. */
 130       pExpr->pRight->flags &= ~EP_Collate;
 131     }else if( sqlite3ExprCollSeq(pParse, pExpr->pLeft)!=0 ){
 132       /* Neither X nor Y have COLLATE operators, but X has a non-default
 133       ** collating sequence.  So add the EP_Collate marker on X to cause
 134       ** it to be searched first. */
 135       pExpr->pLeft->flags |= EP_Collate;
 136     }
 137   }
 138   SWAP(Expr*,pExpr->pRight,pExpr->pLeft);
 139   if( pExpr->op>=TK_GT ){
 140     assert( TK_LT==TK_GT+2 );
 141     assert( TK_GE==TK_LE+2 );
 142     assert( TK_GT>TK_EQ );
 143     assert( TK_GT<TK_LE );
 144     assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE );
 145     pExpr->op = ((pExpr->op-TK_GT)^2)+TK_GT;
 146   }
 147 }
 148
 149 /*
 150 ** Translate from TK_xx operator to WO_xx bitmask.
 151 */
 152 static u16 operatorMask(int op){
 153   u16 c;
 154   assert( allowedOp(op) );
 155   if( op==TK_IN ){
 156     c = WO_IN;
 157   }else if( op==TK_ISNULL ){
 158     c = WO_ISNULL;
 159   }else if( op==TK_IS ){
 160     c = WO_IS;
 161   }else{
 162     assert( (WO_EQ<<(op-TK_EQ)) < 0x7fff );
 163     c = (u16)(WO_EQ<<(op-TK_EQ));
 164   }
 165   assert( op!=TK_ISNULL || c==WO_ISNULL );
 166   assert( op!=TK_IN || c==WO_IN );
 167   assert( op!=TK_EQ || c==WO_EQ );
 168   assert( op!=TK_LT || c==WO_LT );
 169   assert( op!=TK_LE || c==WO_LE );
 170   assert( op!=TK_GT || c==WO_GT );
 171   assert( op!=TK_GE || c==WO_GE );
 172   assert( op!=TK_IS || c==WO_IS );
 173   return c;
 174 }
 175
 176
 177 #ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
 178 /*
 179 ** Check to see if the given expression is a LIKE or GLOB operator that
 180 ** can be optimized using inequality constraints.  Return TRUE if it is
 181 ** so and false if not.
 182 **
 183 ** In order for the operator to be optimizible, the RHS must be a string
 184 ** literal that does not begin with a wildcard.  The LHS must be a column
 185 ** that may only be NULL, a string, or a BLOB, never a number. (This means
 186 ** that virtual tables cannot participate in the LIKE optimization.)  The
 187 ** collating sequence for the column on the LHS must be appropriate for
 188 ** the operator.
 189 */
 190 static int isLikeOrGlob(
 191   Parse *pParse,    /* Parsing and code generating context */
 192   Expr *pExpr,      /* Test this expression */
 193   Expr **ppPrefix,  /* Pointer to TK_STRING expression with pattern prefix */
 194   int *pisComplete, /* True if the only wildcard is % in the last character */
 195   int *pnoCase      /* True if uppercase is equivalent to lowercase */
 196 ){
 197   const u8 *z = 0;         /* String on RHS of LIKE operator */
 198   Expr *pRight, *pLeft;      /* Right and left size of LIKE operator */
 199   ExprList *pList;           /* List of operands to the LIKE operator */
 200   int c;                     /* One character in z[] */
 201   int cnt;                   /* Number of non-wildcard prefix characters */
 202   char wc[4];                /* Wildcard characters */
 203   sqlite3 *db = pParse->db;  /* Database connection */
 204   sqlite3_value *pVal = 0;
 205   int op;                    /* Opcode of pRight */
 206   int rc;                    /* Result code to return */
 207
 208   if( !sqlite3IsLikeFunction(db, pExpr, pnoCase, wc) ){
 209     return 0;
 210   }
 211 #ifdef SQLITE_EBCDIC
 212   if( *pnoCase ) return 0;
 213 #endif
 214   pList = pExpr->x.pList;
 215   pLeft = pList->a[1].pExpr;
 216
 217   pRight = sqlite3ExprSkipCollate(pList->a[0].pExpr);
 218   op = pRight->op;
 219   if( op==TK_VARIABLE && (db->flags & SQLITE_EnableQPSG)==0 ){
 220     Vdbe *pReprepare = pParse->pReprepare;
 221     int iCol = pRight->iColumn;
 222     pVal = sqlite3VdbeGetBoundValue(pReprepare, iCol, SQLITE_AFF_BLOB);
 223     if( pVal && sqlite3_value_type(pVal)==SQLITE_TEXT ){
 224       z = sqlite3_value_text(pVal);
 225     }
 226     sqlite3VdbeSetVarmask(pParse->pVdbe, iCol);
 227     assert( pRight->op==TK_VARIABLE || pRight->op==TK_REGISTER );
 228   }else if( op==TK_STRING ){
 229     z = (u8*)pRight->u.zToken;
 230   }
 231   if( z ){
 232
 233     /* If the RHS begins with a digit or a minus sign, then the LHS must
 234     ** be an ordinary column (not a virtual table column) with TEXT affinity.
 235     ** Otherwise the LHS might be numeric and "lhs >= rhs" would be false
 236     ** even though "lhs LIKE rhs" is true.  But if the RHS does not start
 237     ** with a digit or '-', then "lhs LIKE rhs" will always be false if
 238     ** the LHS is numeric and so the optimization still works.
 239     */
 240     if( sqlite3Isdigit(z[0]) || z[0]=='-' ){
 241       if( pLeft->op!=TK_COLUMN
 242        || sqlite3ExprAffinity(pLeft)!=SQLITE_AFF_TEXT
 243        || IsVirtual(pLeft->pTab)  /* Value might be numeric */
 244       ){
 245         sqlite3ValueFree(pVal);
 246         return 0;
 247       }
 248     }
 249
 250     /* Count the number of prefix characters prior to the first wildcard */
 251     cnt = 0;
 252     while( (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2] ){
 253       cnt++;
 254       if( c==wc[3] && z[cnt]!=0 ) cnt++;
 255     }
 256
 257     /* The optimization is possible only if (1) the pattern does not begin
 258     ** with a wildcard and if (2) the non-wildcard prefix does not end with
 259     ** an (illegal 0xff) character, or (3) the pattern does not consist of
 260     ** a single escape character. The second condition is necessary so
 261     ** that we can increment the prefix key to find an upper bound for the
 262     ** range search. The third is because the caller assumes that the pattern
 263     ** consists of at least one character after all escapes have been
 264     ** removed.  */
 265     if( cnt!=0 && 255!=(u8)z[cnt-1] && (cnt>1 || z[0]!=wc[3]) ){
 266       Expr *pPrefix;
 267
 268       /* A "complete" match if the pattern ends with "*" or "%" */
 269       *pisComplete = c==wc[0] && z[cnt+1]==0;
 270
 271       /* Get the pattern prefix.  Remove all escapes from the prefix. */
 272       pPrefix = sqlite3Expr(db, TK_STRING, (char*)z);
 273       if( pPrefix ){
 274         int iFrom, iTo;
 275         char *zNew = pPrefix->u.zToken;
 276         zNew[cnt] = 0;
 277         for(iFrom=iTo=0; iFrom<cnt; iFrom++){
 278           if( zNew[iFrom]==wc[3] ) iFrom++;
 279           zNew[iTo++] = zNew[iFrom];
 280         }
 281         zNew[iTo] = 0;
 282       }
 283       *ppPrefix = pPrefix;
 284
 285       /* If the RHS pattern is a bound parameter, make arrangements to
 286       ** reprepare the statement when that parameter is rebound */
 287       if( op==TK_VARIABLE ){
 288         Vdbe *v = pParse->pVdbe;
 289         sqlite3VdbeSetVarmask(v, pRight->iColumn);
 290         if( *pisComplete && pRight->u.zToken[1] ){
 291           /* If the rhs of the LIKE expression is a variable, and the current
 292           ** value of the variable means there is no need to invoke the LIKE
 293           ** function, then no OP_Variable will be added to the program.
 294           ** This causes problems for the sqlite3_bind_parameter_name()
 295           ** API. To work around them, add a dummy OP_Variable here.
 296           */
 297           int r1 = sqlite3GetTempReg(pParse);
 298           sqlite3ExprCodeTarget(pParse, pRight, r1);
 299           sqlite3VdbeChangeP3(v, sqlite3VdbeCurrentAddr(v)-1, 0);
 300           sqlite3ReleaseTempReg(pParse, r1);
 301         }
 302       }
 303     }else{
 304       z = 0;
 305     }
 306   }
 307
 308   rc = (z!=0);
 309   sqlite3ValueFree(pVal);
 310   return rc;
 311 }
 312 #endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
 313
 314
 315 #ifndef SQLITE_OMIT_VIRTUALTABLE
 316 /*
 317 ** Check to see if the pExpr expression is a form that needs to be passed
 318 ** to the xBestIndex method of virtual tables.  Forms of interest include:
 319 **
 320 **          Expression                   Virtual Table Operator
 321 **          -----------------------      ---------------------------------
 322 **      1.  column MATCH expr            SQLITE_INDEX_CONSTRAINT_MATCH
 323 **      2.  column GLOB expr             SQLITE_INDEX_CONSTRAINT_GLOB
 324 **      3.  column LIKE expr             SQLITE_INDEX_CONSTRAINT_LIKE
 325 **      4.  column REGEXP expr           SQLITE_INDEX_CONSTRAINT_REGEXP
 326 **      5.  column != expr               SQLITE_INDEX_CONSTRAINT_NE
 327 **      6.  expr != column               SQLITE_INDEX_CONSTRAINT_NE
 328 **      7.  column IS NOT expr           SQLITE_INDEX_CONSTRAINT_ISNOT
 329 **      8.  expr IS NOT column           SQLITE_INDEX_CONSTRAINT_ISNOT
 330 **      9.  column IS NOT NULL           SQLITE_INDEX_CONSTRAINT_ISNOTNULL
 331 **
 332 ** In every case, "column" must be a column of a virtual table.  If there
 333 ** is a match, set *ppLeft to the "column" expression, set *ppRight to the
 334 ** "expr" expression (even though in forms (6) and (8) the column is on the
 335 ** right and the expression is on the left).  Also set *peOp2 to the
 336 ** appropriate virtual table operator.  The return value is 1 or 2 if there
 337 ** is a match.  The usual return is 1, but if the RHS is also a column
 338 ** of virtual table in forms (5) or (7) then return 2.
 339 **
 340 ** If the expression matches none of the patterns above, return 0.
 341 */
 342 static int isAuxiliaryVtabOperator(
 343   Expr *pExpr,                    /* Test this expression */
 344   unsigned char *peOp2,           /* OUT: 0 for MATCH, or else an op2 value */
 345   Expr **ppLeft,                  /* Column expression to left of MATCH/op2 */
 346   Expr **ppRight                  /* Expression to left of MATCH/op2 */
 347 ){
 348   if( pExpr->op==TK_FUNCTION ){
 349     static const struct Op2 {
 350       const char *zOp;
 351       unsigned char eOp2;
 352     } aOp[] = {
 353       { "match",  SQLITE_INDEX_CONSTRAINT_MATCH },
 354       { "glob",   SQLITE_INDEX_CONSTRAINT_GLOB },
 355       { "like",   SQLITE_INDEX_CONSTRAINT_LIKE },
 356       { "regexp", SQLITE_INDEX_CONSTRAINT_REGEXP }
 357     };
 358     ExprList *pList;
 359     Expr *pCol;                     /* Column reference */
 360     int i;
 361
 362     pList = pExpr->x.pList;
 363     if( pList==0 || pList->nExpr!=2 ){
 364       return 0;
 365     }
 366     pCol = pList->a[1].pExpr;
 367     if( pCol->op!=TK_COLUMN || !IsVirtual(pCol->pTab) ){
 368       return 0;
 369     }
 370     for(i=0; i<ArraySize(aOp); i++){
 371       if( sqlite3StrICmp(pExpr->u.zToken, aOp[i].zOp)==0 ){
 372         *peOp2 = aOp[i].eOp2;
 373         *ppRight = pList->a[0].pExpr;
 374         *ppLeft = pCol;
 375         return 1;
 376       }
 377     }
 378   }else if( pExpr->op==TK_NE || pExpr->op==TK_ISNOT || pExpr->op==TK_NOTNULL ){
 379     int res = 0;
 380     Expr *pLeft = pExpr->pLeft;
 381     Expr *pRight = pExpr->pRight;
 382     if( pLeft->op==TK_COLUMN && IsVirtual(pLeft->pTab) ){
 383       res++;
 384     }
 385     if( pRight && pRight->op==TK_COLUMN && IsVirtual(pRight->pTab) ){
 386       res++;
 387       SWAP(Expr*, pLeft, pRight);
 388     }
 389     *ppLeft = pLeft;
 390     *ppRight = pRight;
 391     if( pExpr->op==TK_NE ) *peOp2 = SQLITE_INDEX_CONSTRAINT_NE;
 392     if( pExpr->op==TK_ISNOT ) *peOp2 = SQLITE_INDEX_CONSTRAINT_ISNOT;
 393     if( pExpr->op==TK_NOTNULL ) *peOp2 = SQLITE_INDEX_CONSTRAINT_ISNOTNULL;
 394     return res;
 395   }
 396   return 0;
 397 }
 398 #endif /* SQLITE_OMIT_VIRTUALTABLE */
 399
 400 /*
 401 ** If the pBase expression originated in the ON or USING clause of
 402 ** a join, then transfer the appropriate markings over to derived.
 403 */
 404 static void transferJoinMarkings(Expr *pDerived, Expr *pBase){
 405   if( pDerived ){
 406     pDerived->flags |= pBase->flags & EP_FromJoin;
 407     pDerived->iRightJoinTable = pBase->iRightJoinTable;
 408   }
 409 }
 410
 411 /*
 412 ** Mark term iChild as being a child of term iParent
 413 */
 414 static void markTermAsChild(WhereClause *pWC, int iChild, int iParent){
 415   pWC->a[iChild].iParent = iParent;
 416   pWC->a[iChild].truthProb = pWC->a[iParent].truthProb;
 417   pWC->a[iParent].nChild++;
 418 }
 419
 420 /*
 421 ** Return the N-th AND-connected subterm of pTerm.  Or if pTerm is not
 422 ** a conjunction, then return just pTerm when N==0.  If N is exceeds
 423 ** the number of available subterms, return NULL.
 424 */
 425 static WhereTerm *whereNthSubterm(WhereTerm *pTerm, int N){
 426   if( pTerm->eOperator!=WO_AND ){
 427     return N==0 ? pTerm : 0;
 428   }
 429   if( N<pTerm->u.pAndInfo->wc.nTerm ){
 430     return &pTerm->u.pAndInfo->wc.a[N];
 431   }
 432   return 0;
 433 }
 434
 435 /*
 436 ** Subterms pOne and pTwo are contained within WHERE clause pWC.  The
 437 ** two subterms are in disjunction - they are OR-ed together.
 438 **
 439 ** If these two terms are both of the form:  "A op B" with the same
 440 ** A and B values but different operators and if the operators are
 441 ** compatible (if one is = and the other is <, for example) then
 442 ** add a new virtual AND term to pWC that is the combination of the
 443 ** two.
 444 **
 445 ** Some examples:
 446 **
 447 **    x<y OR x=y    -->     x<=y
 448 **    x=y OR x=y    -->     x=y
 449 **    x<=y OR x<y   -->     x<=y
 450 **
 451 ** The following is NOT generated:
 452 **
 453 **    x<y OR x>y    -->     x!=y
 454 */
 455 static void whereCombineDisjuncts(
 456   SrcList *pSrc,         /* the FROM clause */
 457   WhereClause *pWC,      /* The complete WHERE clause */
 458   WhereTerm *pOne,       /* First disjunct */
 459   WhereTerm *pTwo        /* Second disjunct */
 460 ){
 461   u16 eOp = pOne->eOperator | pTwo->eOperator;
 462   sqlite3 *db;           /* Database connection (for malloc) */
 463   Expr *pNew;            /* New virtual expression */
 464   int op;                /* Operator for the combined expression */
 465   int idxNew;            /* Index in pWC of the next virtual term */
 466
 467   if( (pOne->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return;
 468   if( (pTwo->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return;
 469   if( (eOp & (WO_EQ|WO_LT|WO_LE))!=eOp
 470    && (eOp & (WO_EQ|WO_GT|WO_GE))!=eOp ) return;
 471   assert( pOne->pExpr->pLeft!=0 && pOne->pExpr->pRight!=0 );
 472   assert( pTwo->pExpr->pLeft!=0 && pTwo->pExpr->pRight!=0 );
 473   if( sqlite3ExprCompare(0,pOne->pExpr->pLeft, pTwo->pExpr->pLeft, -1) ) return;
 474   if( sqlite3ExprCompare(0,pOne->pExpr->pRight, pTwo->pExpr->pRight,-1) )return;
 475   /* If we reach this point, it means the two subterms can be combined */
 476   if( (eOp & (eOp-1))!=0 ){
 477     if( eOp & (WO_LT|WO_LE) ){
 478       eOp = WO_LE;
 479     }else{
 480       assert( eOp & (WO_GT|WO_GE) );
 481       eOp = WO_GE;
 482     }
 483   }
 484   db = pWC->pWInfo->pParse->db;
 485   pNew = sqlite3ExprDup(db, pOne->pExpr, 0);
 486   if( pNew==0 ) return;
 487   for(op=TK_EQ; eOp!=(WO_EQ<<(op-TK_EQ)); op++){ assert( op<TK_GE ); }
 488   pNew->op = op;
 489   idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC);
 490   exprAnalyze(pSrc, pWC, idxNew);
 491 }
 492
 493 #if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
 494 /*
 495 ** Analyze a term that consists of two or more OR-connected
 496 ** subterms.  So in:
 497 **
 498 **     ... WHERE  (a=5) AND (b=7 OR c=9 OR d=13) AND (d=13)
 499 **                          ^^^^^^^^^^^^^^^^^^^^
 500 **
 501 ** This routine analyzes terms such as the middle term in the above example.
 502 ** A WhereOrTerm object is computed and attached to the term under
 503 ** analysis, regardless of the outcome of the analysis.  Hence:
 504 **
 505 **     WhereTerm.wtFlags   |=  TERM_ORINFO
 506 **     WhereTerm.u.pOrInfo  =  a dynamically allocated WhereOrTerm object
 507 **
 508 ** The term being analyzed must have two or more of OR-connected subterms.
 509 ** A single subterm might be a set of AND-connected sub-subterms.
 510 ** Examples of terms under analysis:
 511 **
 512 **     (A)     t1.x=t2.y OR t1.x=t2.z OR t1.y=15 OR t1.z=t3.a+5
 513 **     (B)     x=expr1 OR expr2=x OR x=expr3
 514 **     (C)     t1.x=t2.y OR (t1.x=t2.z AND t1.y=15)
 515 **     (D)     x=expr1 OR (y>11 AND y<22 AND z LIKE '*hello*')
 516 **     (E)     (p.a=1 AND q.b=2 AND r.c=3) OR (p.x=4 AND q.y=5 AND r.z=6)
 517 **     (F)     x>A OR (x=A AND y>=B)
 518 **
 519 ** CASE 1:
 520 **
 521 ** If all subterms are of the form T.C=expr for some single column of C and
 522 ** a single table T (as shown in example B above) then create a new virtual
 523 ** term that is an equivalent IN expression.  In other words, if the term
 524 ** being analyzed is:
 525 **
 526 **      x = expr1  OR  expr2 = x  OR  x = expr3
 527 **
 528 ** then create a new virtual term like this:
 529 **
 530 **      x IN (expr1,expr2,expr3)
 531 **
 532 ** CASE 2:
 533 **
 534 ** If there are exactly two disjuncts and one side has x>A and the other side
 535 ** has x=A (for the same x and A) then add a new virtual conjunct term to the
 536 ** WHERE clause of the form "x>=A".  Example:
 537 **
 538 **      x>A OR (x=A AND y>B)    adds:    x>=A
 539 **
 540 ** The added conjunct can sometimes be helpful in query planning.
 541 **
 542 ** CASE 3:
 543 **
 544 ** If all subterms are indexable by a single table T, then set
 545 **
 546 **     WhereTerm.eOperator              =  WO_OR
 547 **     WhereTerm.u.pOrInfo->indexable  |=  the cursor number for table T
 548 **
 549 ** A subterm is "indexable" if it is of the form
 550 ** "T.C <op> <expr>" where C is any column of table T and
 551 ** <op> is one of "=", "<", "<=", ">", ">=", "IS NULL", or "IN".
 552 ** A subterm is also indexable if it is an AND of two or more
 553 ** subsubterms at least one of which is indexable.  Indexable AND
 554 ** subterms have their eOperator set to WO_AND and they have
 555 ** u.pAndInfo set to a dynamically allocated WhereAndTerm object.
 556 **
 557 ** From another point of view, "indexable" means that the subterm could
 558 ** potentially be used with an index if an appropriate index exists.
 559 ** This analysis does not consider whether or not the index exists; that
 560 ** is decided elsewhere.  This analysis only looks at whether subterms
 561 ** appropriate for indexing exist.
 562 **
 563 ** All examples A through E above satisfy case 3.  But if a term
 564 ** also satisfies case 1 (such as B) we know that the optimizer will
 565 ** always prefer case 1, so in that case we pretend that case 3 is not
 566 ** satisfied.
 567 **
 568 ** It might be the case that multiple tables are indexable.  For example,
 569 ** (E) above is indexable on tables P, Q, and R.
 570 **
 571 ** Terms that satisfy case 3 are candidates for lookup by using
 572 ** separate indices to find rowids for each subterm and composing
 573 ** the union of all rowids using a RowSet object.  This is similar
 574 ** to "bitmap indices" in other database engines.
 575 **
 576 ** OTHERWISE:
 577 **
 578 ** If none of cases 1, 2, or 3 apply, then leave the eOperator set to
 579 ** zero.  This term is not useful for search.
 580 */
 581 static void exprAnalyzeOrTerm(
 582   SrcList *pSrc,            /* the FROM clause */
 583   WhereClause *pWC,         /* the complete WHERE clause */
 584   int idxTerm               /* Index of the OR-term to be analyzed */
 585 ){
 586   WhereInfo *pWInfo = pWC->pWInfo;        /* WHERE clause processing context */
 587   Parse *pParse = pWInfo->pParse;         /* Parser context */
 588   sqlite3 *db = pParse->db;               /* Database connection */
 589   WhereTerm *pTerm = &pWC->a[idxTerm];    /* The term to be analyzed */
 590   Expr *pExpr = pTerm->pExpr;             /* The expression of the term */
 591   int i;                                  /* Loop counters */
 592   WhereClause *pOrWc;       /* Breakup of pTerm into subterms */
 593   WhereTerm *pOrTerm;       /* A Sub-term within the pOrWc */
 594   WhereOrInfo *pOrInfo;     /* Additional information associated with pTerm */
 595   Bitmask chngToIN;         /* Tables that might satisfy case 1 */
 596   Bitmask indexable;        /* Tables that are indexable, satisfying case 2 */
 597
 598   /*
 599   ** Break the OR clause into its separate subterms.  The subterms are
 600   ** stored in a WhereClause structure containing within the WhereOrInfo
 601   ** object that is attached to the original OR clause term.
 602   */
 603   assert( (pTerm->wtFlags & (TERM_DYNAMIC|TERM_ORINFO|TERM_ANDINFO))==0 );
 604   assert( pExpr->op==TK_OR );
 605   pTerm->u.pOrInfo = pOrInfo = sqlite3DbMallocZero(db, sizeof(*pOrInfo));
 606   if( pOrInfo==0 ) return;
 607   pTerm->wtFlags |= TERM_ORINFO;
 608   pOrWc = &pOrInfo->wc;
 609   memset(pOrWc->aStatic, 0, sizeof(pOrWc->aStatic));
 610   sqlite3WhereClauseInit(pOrWc, pWInfo);
 611   sqlite3WhereSplit(pOrWc, pExpr, TK_OR);
 612   sqlite3WhereExprAnalyze(pSrc, pOrWc);
 613   if( db->mallocFailed ) return;
 614   assert( pOrWc->nTerm>=2 );
 615
 616   /*
 617   ** Compute the set of tables that might satisfy cases 1 or 3.
 618   */
 619   indexable = ~(Bitmask)0;
 620   chngToIN = ~(Bitmask)0;
 621   for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0 && indexable; i--, pOrTerm++){
 622     if( (pOrTerm->eOperator & WO_SINGLE)==0 ){
 623       WhereAndInfo *pAndInfo;
 624       assert( (pOrTerm->wtFlags & (TERM_ANDINFO|TERM_ORINFO))==0 );
 625       chngToIN = 0;
 626       pAndInfo = sqlite3DbMallocRawNN(db, sizeof(*pAndInfo));
 627       if( pAndInfo ){
 628         WhereClause *pAndWC;
 629         WhereTerm *pAndTerm;
 630         int j;
 631         Bitmask b = 0;
 632         pOrTerm->u.pAndInfo = pAndInfo;
 633         pOrTerm->wtFlags |= TERM_ANDINFO;
 634         pOrTerm->eOperator = WO_AND;
 635         pAndWC = &pAndInfo->wc;
 636         memset(pAndWC->aStatic, 0, sizeof(pAndWC->aStatic));
 637         sqlite3WhereClauseInit(pAndWC, pWC->pWInfo);
 638         sqlite3WhereSplit(pAndWC, pOrTerm->pExpr, TK_AND);
 639         sqlite3WhereExprAnalyze(pSrc, pAndWC);
 640         pAndWC->pOuter = pWC;
 641         if( !db->mallocFailed ){
 642           for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){
 643             assert( pAndTerm->pExpr );
 644             if( allowedOp(pAndTerm->pExpr->op)
 645              || pAndTerm->eOperator==WO_AUX
 646             ){
 647               b |= sqlite3WhereGetMask(&pWInfo->sMaskSet, pAndTerm->leftCursor);
 648             }
 649           }
 650         }
 651         indexable &= b;
 652       }
 653     }else if( pOrTerm->wtFlags & TERM_COPIED ){
 654       /* Skip this term for now.  We revisit it when we process the
 655       ** corresponding TERM_VIRTUAL term */
 656     }else{
 657       Bitmask b;
 658       b = sqlite3WhereGetMask(&pWInfo->sMaskSet, pOrTerm->leftCursor);
 659       if( pOrTerm->wtFlags & TERM_VIRTUAL ){
 660         WhereTerm *pOther = &pOrWc->a[pOrTerm->iParent];
 661         b |= sqlite3WhereGetMask(&pWInfo->sMaskSet, pOther->leftCursor);
 662       }
 663       indexable &= b;
 664       if( (pOrTerm->eOperator & WO_EQ)==0 ){
 665         chngToIN = 0;
 666       }else{
 667         chngToIN &= b;
 668       }
 669     }
 670   }
 671
 672   /*
 673   ** Record the set of tables that satisfy case 3.  The set might be
 674   ** empty.
 675   */
 676   pOrInfo->indexable = indexable;
 677   if( indexable ){
 678     pTerm->eOperator = WO_OR;
 679     pWC->hasOr = 1;
 680   }else{
 681     pTerm->eOperator = WO_OR;
 682   }
 683
 684   /* For a two-way OR, attempt to implementation case 2.
 685   */
 686   if( indexable && pOrWc->nTerm==2 ){
 687     int iOne = 0;
 688     WhereTerm *pOne;
 689     while( (pOne = whereNthSubterm(&pOrWc->a[0],iOne++))!=0 ){
 690       int iTwo = 0;
 691       WhereTerm *pTwo;
 692       while( (pTwo = whereNthSubterm(&pOrWc->a[1],iTwo++))!=0 ){
 693         whereCombineDisjuncts(pSrc, pWC, pOne, pTwo);
 694       }
 695     }
 696   }
 697
 698   /*
 699   ** chngToIN holds a set of tables that *might* satisfy case 1.  But
 700   ** we have to do some additional checking to see if case 1 really
 701   ** is satisfied.
 702   **
 703   ** chngToIN will hold either 0, 1, or 2 bits.  The 0-bit case means
 704   ** that there is no possibility of transforming the OR clause into an
 705   ** IN operator because one or more terms in the OR clause contain
 706   ** something other than == on a column in the single table.  The 1-bit
 707   ** case means that every term of the OR clause is of the form
 708   ** "table.column=expr" for some single table.  The one bit that is set
 709   ** will correspond to the common table.  We still need to check to make
 710   ** sure the same column is used on all terms.  The 2-bit case is when
 711   ** the all terms are of the form "table1.column=table2.column".  It
 712   ** might be possible to form an IN operator with either table1.column
 713   ** or table2.column as the LHS if either is common to every term of
 714   ** the OR clause.
 715   **
 716   ** Note that terms of the form "table.column1=table.column2" (the
 717   ** same table on both sizes of the ==) cannot be optimized.
 718   */
 719   if( chngToIN ){
 720     int okToChngToIN = 0;     /* True if the conversion to IN is valid */
 721     int iColumn = -1;         /* Column index on lhs of IN operator */
 722     int iCursor = -1;         /* Table cursor common to all terms */
 723     int j = 0;                /* Loop counter */
 724
 725     /* Search for a table and column that appears on one side or the
 726     ** other of the == operator in every subterm.  That table and column
 727     ** will be recorded in iCursor and iColumn.  There might not be any
 728     ** such table and column.  Set okToChngToIN if an appropriate table
 729     ** and column is found but leave okToChngToIN false if not found.
 730     */
 731     for(j=0; j<2 && !okToChngToIN; j++){
 732       pOrTerm = pOrWc->a;
 733       for(i=pOrWc->nTerm-1; i>=0; i--, pOrTerm++){
 734         assert( pOrTerm->eOperator & WO_EQ );
 735         pOrTerm->wtFlags &= ~TERM_OR_OK;
 736         if( pOrTerm->leftCursor==iCursor ){
 737           /* This is the 2-bit case and we are on the second iteration and
 738           ** current term is from the first iteration.  So skip this term. */
 739           assert( j==1 );
 740           continue;
 741         }
 742         if( (chngToIN & sqlite3WhereGetMask(&pWInfo->sMaskSet,
 743                                             pOrTerm->leftCursor))==0 ){
 744           /* This term must be of the form t1.a==t2.b where t2 is in the
 745           ** chngToIN set but t1 is not.  This term will be either preceded
 746           ** or follwed by an inverted copy (t2.b==t1.a).  Skip this term
 747           ** and use its inversion. */
 748           testcase( pOrTerm->wtFlags & TERM_COPIED );
 749           testcase( pOrTerm->wtFlags & TERM_VIRTUAL );
 750           assert( pOrTerm->wtFlags & (TERM_COPIED|TERM_VIRTUAL) );
 751           continue;
 752         }
 753         iColumn = pOrTerm->u.leftColumn;
 754         iCursor = pOrTerm->leftCursor;
 755         break;
 756       }
 757       if( i<0 ){
 758         /* No candidate table+column was found.  This can only occur
 759         ** on the second iteration */
 760         assert( j==1 );
 761         assert( IsPowerOfTwo(chngToIN) );
 762         assert( chngToIN==sqlite3WhereGetMask(&pWInfo->sMaskSet, iCursor) );
 763         break;
 764       }
 765       testcase( j==1 );
 766
 767       /* We have found a candidate table and column.  Check to see if that
 768       ** table and column is common to every term in the OR clause */
 769       okToChngToIN = 1;
 770       for(; i>=0 && okToChngToIN; i--, pOrTerm++){
 771         assert( pOrTerm->eOperator & WO_EQ );
 772         if( pOrTerm->leftCursor!=iCursor ){
 773           pOrTerm->wtFlags &= ~TERM_OR_OK;
 774         }else if( pOrTerm->u.leftColumn!=iColumn ){
 775           okToChngToIN = 0;
 776         }else{
 777           int affLeft, affRight;
 778           /* If the right-hand side is also a column, then the affinities
 779           ** of both right and left sides must be such that no type
 780           ** conversions are required on the right.  (Ticket #2249)
 781           */
 782           affRight = sqlite3ExprAffinity(pOrTerm->pExpr->pRight);
 783           affLeft = sqlite3ExprAffinity(pOrTerm->pExpr->pLeft);
 784           if( affRight!=0 && affRight!=affLeft ){
 785             okToChngToIN = 0;
 786           }else{
 787             pOrTerm->wtFlags |= TERM_OR_OK;
 788           }
 789         }
 790       }
 791     }
 792
 793     /* At this point, okToChngToIN is true if original pTerm satisfies
 794     ** case 1.  In that case, construct a new virtual term that is
 795     ** pTerm converted into an IN operator.
 796     */
 797     if( okToChngToIN ){
 798       Expr *pDup;            /* A transient duplicate expression */
 799       ExprList *pList = 0;   /* The RHS of the IN operator */
 800       Expr *pLeft = 0;       /* The LHS of the IN operator */
 801       Expr *pNew;            /* The complete IN operator */
 802
 803       for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0; i--, pOrTerm++){
 804         if( (pOrTerm->wtFlags & TERM_OR_OK)==0 ) continue;
 805         assert( pOrTerm->eOperator & WO_EQ );
 806         assert( pOrTerm->leftCursor==iCursor );
 807         assert( pOrTerm->u.leftColumn==iColumn );
 808         pDup = sqlite3ExprDup(db, pOrTerm->pExpr->pRight, 0);
 809         pList = sqlite3ExprListAppend(pWInfo->pParse, pList, pDup);
 810         pLeft = pOrTerm->pExpr->pLeft;
 811       }
 812       assert( pLeft!=0 );
 813       pDup = sqlite3ExprDup(db, pLeft, 0);
 814       pNew = sqlite3PExpr(pParse, TK_IN, pDup, 0);
 815       if( pNew ){
 816         int idxNew;
 817         transferJoinMarkings(pNew, pExpr);
 818         assert( !ExprHasProperty(pNew, EP_xIsSelect) );
 819         pNew->x.pList = pList;
 820         idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC);
 821         testcase( idxNew==0 );
 822         exprAnalyze(pSrc, pWC, idxNew);
 823         pTerm = &pWC->a[idxTerm];
 824         markTermAsChild(pWC, idxNew, idxTerm);
 825       }else{
 826         sqlite3ExprListDelete(db, pList);
 827       }
 828     }
 829   }
 830 }
 831 #endif /* !SQLITE_OMIT_OR_OPTIMIZATION && !SQLITE_OMIT_SUBQUERY */
 832
 833 /*
 834 ** We already know that pExpr is a binary operator where both operands are
 835 ** column references.  This routine checks to see if pExpr is an equivalence
 836 ** relation:
 837 **   1.  The SQLITE_Transitive optimization must be enabled
 838 **   2.  Must be either an == or an IS operator
 839 **   3.  Not originating in the ON clause of an OUTER JOIN
 840 **   4.  The affinities of A and B must be compatible
 841 **   5a. Both operands use the same collating sequence OR
 842 **   5b. The overall collating sequence is BINARY
 843 ** If this routine returns TRUE, that means that the RHS can be substituted
 844 ** for the LHS anyplace else in the WHERE clause where the LHS column occurs.
 845 ** This is an optimization.  No harm comes from returning 0.  But if 1 is
 846 ** returned when it should not be, then incorrect answers might result.
 847 */
 848 static int termIsEquivalence(Parse *pParse, Expr *pExpr){
 849   char aff1, aff2;
 850   CollSeq *pColl;
 851   if( !OptimizationEnabled(pParse->db, SQLITE_Transitive) ) return 0;
 852   if( pExpr->op!=TK_EQ && pExpr->op!=TK_IS ) return 0;
 853   if( ExprHasProperty(pExpr, EP_FromJoin) ) return 0;
 854   aff1 = sqlite3ExprAffinity(pExpr->pLeft);
 855   aff2 = sqlite3ExprAffinity(pExpr->pRight);
 856   if( aff1!=aff2
 857    && (!sqlite3IsNumericAffinity(aff1) || !sqlite3IsNumericAffinity(aff2))
 858   ){
 859     return 0;
 860   }
 861   pColl = sqlite3BinaryCompareCollSeq(pParse, pExpr->pLeft, pExpr->pRight);
 862   if( pColl==0 || sqlite3StrICmp(pColl->zName, "BINARY")==0 ) return 1;
 863   return sqlite3ExprCollSeqMatch(pParse, pExpr->pLeft, pExpr->pRight);
 864 }
 865
 866 /*
 867 ** Recursively walk the expressions of a SELECT statement and generate
 868 ** a bitmask indicating which tables are used in that expression
 869 ** tree.
 870 */
 871 static Bitmask exprSelectUsage(WhereMaskSet *pMaskSet, Select *pS){
 872   Bitmask mask = 0;
 873   while( pS ){
 874     SrcList *pSrc = pS->pSrc;
 875     mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pEList);
 876     mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pGroupBy);
 877     mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pOrderBy);
 878     mask |= sqlite3WhereExprUsage(pMaskSet, pS->pWhere);
 879     mask |= sqlite3WhereExprUsage(pMaskSet, pS->pHaving);
 880     if( ALWAYS(pSrc!=0) ){
 881       int i;
 882       for(i=0; i<pSrc->nSrc; i++){
 883         mask |= exprSelectUsage(pMaskSet, pSrc->a[i].pSelect);
 884         mask |= sqlite3WhereExprUsage(pMaskSet, pSrc->a[i].pOn);
 885         if( pSrc->a[i].fg.isTabFunc ){
 886           mask |= sqlite3WhereExprListUsage(pMaskSet, pSrc->a[i].u1.pFuncArg);
 887         }
 888       }
 889     }
 890     pS = pS->pPrior;
 891   }
 892   return mask;
 893 }
 894
 895 /*
 896 ** Expression pExpr is one operand of a comparison operator that might
 897 ** be useful for indexing.  This routine checks to see if pExpr appears
 898 ** in any index.  Return TRUE (1) if pExpr is an indexed term and return
 899 ** FALSE (0) if not.  If TRUE is returned, also set aiCurCol[0] to the cursor
 900 ** number of the table that is indexed and aiCurCol[1] to the column number
 901 ** of the column that is indexed, or XN_EXPR (-2) if an expression is being
 902 ** indexed.
 903 **
 904 ** If pExpr is a TK_COLUMN column reference, then this routine always returns
 905 ** true even if that particular column is not indexed, because the column
 906 ** might be added to an automatic index later.
 907 */
 908 static SQLITE_NOINLINE int exprMightBeIndexed2(
 909   SrcList *pFrom,        /* The FROM clause */
 910   Bitmask mPrereq,       /* Bitmask of FROM clause terms referenced by pExpr */
 911   int *aiCurCol,         /* Write the referenced table cursor and column here */
 912   Expr *pExpr            /* An operand of a comparison operator */
 913 ){
 914   Index *pIdx;
 915   int i;
 916   int iCur;
 917   for(i=0; mPrereq>1; i++, mPrereq>>=1){}
 918   iCur = pFrom->a[i].iCursor;
 919   for(pIdx=pFrom->a[i].pTab->pIndex; pIdx; pIdx=pIdx->pNext){
 920     if( pIdx->aColExpr==0 ) continue;
 921     for(i=0; i<pIdx->nKeyCol; i++){
 922       if( pIdx->aiColumn[i]!=XN_EXPR ) continue;
 923       if( sqlite3ExprCompareSkip(pExpr, pIdx->aColExpr->a[i].pExpr, iCur)==0 ){
 924         aiCurCol[0] = iCur;
 925         aiCurCol[1] = XN_EXPR;
 926         return 1;
 927       }
 928     }
 929   }
 930   return 0;
 931 }
 932 static int exprMightBeIndexed(
 933   SrcList *pFrom,        /* The FROM clause */
 934   Bitmask mPrereq,       /* Bitmask of FROM clause terms referenced by pExpr */
 935   int *aiCurCol,         /* Write the referenced table cursor & column here */
 936   Expr *pExpr,           /* An operand of a comparison operator */
 937   int op                 /* The specific comparison operator */
 938 ){
 939   /* If this expression is a vector to the left or right of a
 940   ** inequality constraint (>, <, >= or <=), perform the processing
 941   ** on the first element of the vector.  */
 942   assert( TK_GT+1==TK_LE && TK_GT+2==TK_LT && TK_GT+3==TK_GE );
 943   assert( TK_IS<TK_GE && TK_ISNULL<TK_GE && TK_IN<TK_GE );
 944   assert( op<=TK_GE );
 945   if( pExpr->op==TK_VECTOR && (op>=TK_GT && ALWAYS(op<=TK_GE)) ){
 946     pExpr = pExpr->x.pList->a[0].pExpr;
 947   }
 948
 949   if( pExpr->op==TK_COLUMN ){
 950     aiCurCol[0] = pExpr->iTable;
 951     aiCurCol[1] = pExpr->iColumn;
 952     return 1;
 953   }
 954   if( mPrereq==0 ) return 0;                 /* No table references */
 955   if( (mPrereq&(mPrereq-1))!=0 ) return 0;   /* Refs more than one table */
 956   return exprMightBeIndexed2(pFrom,mPrereq,aiCurCol,pExpr);
 957 }
 958
 959 /*
 960 ** The input to this routine is an WhereTerm structure with only the
 961 ** "pExpr" field filled in.  The job of this routine is to analyze the
 962 ** subexpression and populate all the other fields of the WhereTerm
 963 ** structure.
 964 **
 965 ** If the expression is of the form "<expr> <op> X" it gets commuted
 966 ** to the standard form of "X <op> <expr>".
 967 **
 968 ** If the expression is of the form "X <op> Y" where both X and Y are
 969 ** columns, then the original expression is unchanged and a new virtual
 970 ** term of the form "Y <op> X" is added to the WHERE clause and
 971 ** analyzed separately.  The original term is marked with TERM_COPIED
 972 ** and the new term is marked with TERM_DYNAMIC (because it's pExpr
 973 ** needs to be freed with the WhereClause) and TERM_VIRTUAL (because it
 974 ** is a commuted copy of a prior term.)  The original term has nChild=1
 975 ** and the copy has idxParent set to the index of the original term.
 976 */
 977 static void exprAnalyze(
 978   SrcList *pSrc,            /* the FROM clause */
 979   WhereClause *pWC,         /* the WHERE clause */
 980   int idxTerm               /* Index of the term to be analyzed */
 981 ){
 982   WhereInfo *pWInfo = pWC->pWInfo; /* WHERE clause processing context */
 983   WhereTerm *pTerm;                /* The term to be analyzed */
 984   WhereMaskSet *pMaskSet;          /* Set of table index masks */
 985   Expr *pExpr;                     /* The expression to be analyzed */
 986   Bitmask prereqLeft;              /* Prerequesites of the pExpr->pLeft */
 987   Bitmask prereqAll;               /* Prerequesites of pExpr */
 988   Bitmask extraRight = 0;          /* Extra dependencies on LEFT JOIN */
 989   Expr *pStr1 = 0;                 /* RHS of LIKE/GLOB operator */
 990   int isComplete = 0;              /* RHS of LIKE/GLOB ends with wildcard */
 991   int noCase = 0;                  /* uppercase equivalent to lowercase */
 992   int op;                          /* Top-level operator.  pExpr->op */
 993   Parse *pParse = pWInfo->pParse;  /* Parsing context */
 994   sqlite3 *db = pParse->db;        /* Database connection */
 995   unsigned char eOp2 = 0;          /* op2 value for LIKE/REGEXP/GLOB */
 996   int nLeft;                       /* Number of elements on left side vector */
 997
 998   if( db->mallocFailed ){
 999     return;
1000   }
1001   pTerm = &pWC->a[idxTerm];
1002   pMaskSet = &pWInfo->sMaskSet;
1003   pExpr = pTerm->pExpr;
1004   assert( pExpr->op!=TK_AS && pExpr->op!=TK_COLLATE );
1005   prereqLeft = sqlite3WhereExprUsage(pMaskSet, pExpr->pLeft);
1006   op = pExpr->op;
1007   if( op==TK_IN ){
1008     assert( pExpr->pRight==0 );
1009     if( sqlite3ExprCheckIN(pParse, pExpr) ) return;
1010     if( ExprHasProperty(pExpr, EP_xIsSelect) ){
1011       pTerm->prereqRight = exprSelectUsage(pMaskSet, pExpr->x.pSelect);
1012     }else{
1013       pTerm->prereqRight = sqlite3WhereExprListUsage(pMaskSet, pExpr->x.pList);
1014     }
1015   }else if( op==TK_ISNULL ){
1016     pTerm->prereqRight = 0;
1017   }else{
1018     pTerm->prereqRight = sqlite3WhereExprUsage(pMaskSet, pExpr->pRight);
1019   }
1020   pMaskSet->bVarSelect = 0;
1021   prereqAll = sqlite3WhereExprUsageNN(pMaskSet, pExpr);
1022   if( pMaskSet->bVarSelect ) pTerm->wtFlags |= TERM_VARSELECT;
1023   if( ExprHasProperty(pExpr, EP_FromJoin) ){
1024     Bitmask x = sqlite3WhereGetMask(pMaskSet, pExpr->iRightJoinTable);
1025     prereqAll |= x;
1026     extraRight = x-1;  /* ON clause terms may not be used with an index
1027                        ** on left table of a LEFT JOIN.  Ticket #3015 */
1028     if( (prereqAll>>1)>=x ){
1029       sqlite3ErrorMsg(pParse, "ON clause references tables to its right");
1030       return;
1031     }
1032   }
1033   pTerm->prereqAll = prereqAll;
1034   pTerm->leftCursor = -1;
1035   pTerm->iParent = -1;
1036   pTerm->eOperator = 0;
1037   if( allowedOp(op) ){
1038     int aiCurCol[2];
1039     Expr *pLeft = sqlite3ExprSkipCollate(pExpr->pLeft);
1040     Expr *pRight = sqlite3ExprSkipCollate(pExpr->pRight);
1041     u16 opMask = (pTerm->prereqRight & prereqLeft)==0 ? WO_ALL : WO_EQUIV;
1042
1043     if( pTerm->iField>0 ){
1044       assert( op==TK_IN );
1045       assert( pLeft->op==TK_VECTOR );
1046       pLeft = pLeft->x.pList->a[pTerm->iField-1].pExpr;
1047     }
1048
1049     if( exprMightBeIndexed(pSrc, prereqLeft, aiCurCol, pLeft, op) ){
1050       pTerm->leftCursor = aiCurCol[0];
1051       pTerm->u.leftColumn = aiCurCol[1];
1052       pTerm->eOperator = operatorMask(op) & opMask;
1053     }
1054     if( op==TK_IS ) pTerm->wtFlags |= TERM_IS;
1055     if( pRight
1056      && exprMightBeIndexed(pSrc, pTerm->prereqRight, aiCurCol, pRight, op)
1057     ){
1058       WhereTerm *pNew;
1059       Expr *pDup;
1060       u16 eExtraOp = 0;        /* Extra bits for pNew->eOperator */
1061       assert( pTerm->iField==0 );
1062       if( pTerm->leftCursor>=0 ){
1063         int idxNew;
1064         pDup = sqlite3ExprDup(db, pExpr, 0);
1065         if( db->mallocFailed ){
1066           sqlite3ExprDelete(db, pDup);
1067           return;
1068         }
1069         idxNew = whereClauseInsert(pWC, pDup, TERM_VIRTUAL|TERM_DYNAMIC);
1070         if( idxNew==0 ) return;
1071         pNew = &pWC->a[idxNew];
1072         markTermAsChild(pWC, idxNew, idxTerm);
1073         if( op==TK_IS ) pNew->wtFlags |= TERM_IS;
1074         pTerm = &pWC->a[idxTerm];
1075         pTerm->wtFlags |= TERM_COPIED;
1076
1077         if( termIsEquivalence(pParse, pDup) ){
1078           pTerm->eOperator |= WO_EQUIV;
1079           eExtraOp = WO_EQUIV;
1080         }
1081       }else{
1082         pDup = pExpr;
1083         pNew = pTerm;
1084       }
1085       exprCommute(pParse, pDup);
1086       pNew->leftCursor = aiCurCol[0];
1087       pNew->u.leftColumn = aiCurCol[1];
1088       testcase( (prereqLeft | extraRight) != prereqLeft );
1089       pNew->prereqRight = prereqLeft | extraRight;
1090       pNew->prereqAll = prereqAll;
1091       pNew->eOperator = (operatorMask(pDup->op) + eExtraOp) & opMask;
1092     }
1093   }
1094
1095 #ifndef SQLITE_OMIT_BETWEEN_OPTIMIZATION
1096   /* If a term is the BETWEEN operator, create two new virtual terms
1097   ** that define the range that the BETWEEN implements.  For example:
1098   **
1099   **      a BETWEEN b AND c
1100   **
1101   ** is converted into:
1102   **
1103   **      (a BETWEEN b AND c) AND (a>=b) AND (a<=c)
1104   **
1105   ** The two new terms are added onto the end of the WhereClause object.
1106   ** The new terms are "dynamic" and are children of the original BETWEEN
1107   ** term.  That means that if the BETWEEN term is coded, the children are
1108   ** skipped.  Or, if the children are satisfied by an index, the original
1109   ** BETWEEN term is skipped.
1110   */
1111   else if( pExpr->op==TK_BETWEEN && pWC->op==TK_AND ){
1112     ExprList *pList = pExpr->x.pList;
1113     int i;
1114     static const u8 ops[] = {TK_GE, TK_LE};
1115     assert( pList!=0 );
1116     assert( pList->nExpr==2 );
1117     for(i=0; i<2; i++){
1118       Expr *pNewExpr;
1119       int idxNew;
1120       pNewExpr = sqlite3PExpr(pParse, ops[i],
1121                              sqlite3ExprDup(db, pExpr->pLeft, 0),
1122                              sqlite3ExprDup(db, pList->a[i].pExpr, 0));
1123       transferJoinMarkings(pNewExpr, pExpr);
1124       idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
1125       testcase( idxNew==0 );
1126       exprAnalyze(pSrc, pWC, idxNew);
1127       pTerm = &pWC->a[idxTerm];
1128       markTermAsChild(pWC, idxNew, idxTerm);
1129     }
1130   }
1131 #endif /* SQLITE_OMIT_BETWEEN_OPTIMIZATION */
1132
1133 #if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
1134   /* Analyze a term that is composed of two or more subterms connected by
1135   ** an OR operator.
1136   */
1137   else if( pExpr->op==TK_OR ){
1138     assert( pWC->op==TK_AND );
1139     exprAnalyzeOrTerm(pSrc, pWC, idxTerm);
1140     pTerm = &pWC->a[idxTerm];
1141   }
1142 #endif /* SQLITE_OMIT_OR_OPTIMIZATION */
1143
1144 #ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
1145   /* Add constraints to reduce the search space on a LIKE or GLOB
1146   ** operator.
1147   **
1148   ** A like pattern of the form "x LIKE 'aBc%'" is changed into constraints
1149   **
1150   **          x>='ABC' AND x<'abd' AND x LIKE 'aBc%'
1151   **
1152   ** The last character of the prefix "abc" is incremented to form the
1153   ** termination condition "abd".  If case is not significant (the default
1154   ** for LIKE) then the lower-bound is made all uppercase and the upper-
1155   ** bound is made all lowercase so that the bounds also work when comparing
1156   ** BLOBs.
1157   */
1158   if( pWC->op==TK_AND
1159    && isLikeOrGlob(pParse, pExpr, &pStr1, &isComplete, &noCase)
1160   ){
1161     Expr *pLeft;       /* LHS of LIKE/GLOB operator */
1162     Expr *pStr2;       /* Copy of pStr1 - RHS of LIKE/GLOB operator */
1163     Expr *pNewExpr1;
1164     Expr *pNewExpr2;
1165     int idxNew1;
1166     int idxNew2;
1167     const char *zCollSeqName;     /* Name of collating sequence */
1168     const u16 wtFlags = TERM_LIKEOPT | TERM_VIRTUAL | TERM_DYNAMIC;
1169
1170     pLeft = pExpr->x.pList->a[1].pExpr;
1171     pStr2 = sqlite3ExprDup(db, pStr1, 0);
1172
1173     /* Convert the lower bound to upper-case and the upper bound to
1174     ** lower-case (upper-case is less than lower-case in ASCII) so that
1175     ** the range constraints also work for BLOBs
1176     */
1177     if( noCase && !pParse->db->mallocFailed ){
1178       int i;
1179       char c;
1180       pTerm->wtFlags |= TERM_LIKE;
1181       for(i=0; (c = pStr1->u.zToken[i])!=0; i++){
1182         pStr1->u.zToken[i] = sqlite3Toupper(c);
1183         pStr2->u.zToken[i] = sqlite3Tolower(c);
1184       }
1185     }
1186
1187     if( !db->mallocFailed ){
1188       u8 c, *pC;       /* Last character before the first wildcard */
1189       pC = (u8*)&pStr2->u.zToken[sqlite3Strlen30(pStr2->u.zToken)-1];
1190       c = *pC;
1191       if( noCase ){
1192         /* The point is to increment the last character before the first
1193         ** wildcard.  But if we increment '@', that will push it into the
1194         ** alphabetic range where case conversions will mess up the
1195         ** inequality.  To avoid this, make sure to also run the full
1196         ** LIKE on all candidate expressions by clearing the isComplete flag
1197         */
1198         if( c=='A'-1 ) isComplete = 0;
1199         c = sqlite3UpperToLower[c];
1200       }
1201       *pC = c + 1;
1202     }
1203     zCollSeqName = noCase ? "NOCASE" : "BINARY";
1204     pNewExpr1 = sqlite3ExprDup(db, pLeft, 0);
1205     pNewExpr1 = sqlite3PExpr(pParse, TK_GE,
1206            sqlite3ExprAddCollateString(pParse,pNewExpr1,zCollSeqName),
1207            pStr1);
1208     transferJoinMarkings(pNewExpr1, pExpr);
1209     idxNew1 = whereClauseInsert(pWC, pNewExpr1, wtFlags);
1210     testcase( idxNew1==0 );
1211     exprAnalyze(pSrc, pWC, idxNew1);
1212     pNewExpr2 = sqlite3ExprDup(db, pLeft, 0);
1213     pNewExpr2 = sqlite3PExpr(pParse, TK_LT,
1214            sqlite3ExprAddCollateString(pParse,pNewExpr2,zCollSeqName),
1215            pStr2);
1216     transferJoinMarkings(pNewExpr2, pExpr);
1217     idxNew2 = whereClauseInsert(pWC, pNewExpr2, wtFlags);
1218     testcase( idxNew2==0 );
1219     exprAnalyze(pSrc, pWC, idxNew2);
1220     pTerm = &pWC->a[idxTerm];
1221     if( isComplete ){
1222       markTermAsChild(pWC, idxNew1, idxTerm);
1223       markTermAsChild(pWC, idxNew2, idxTerm);
1224     }
1225   }
1226 #endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
1227
1228 #ifndef SQLITE_OMIT_VIRTUALTABLE
1229   /* Add a WO_AUX auxiliary term to the constraint set if the
1230   ** current expression is of the form "column OP expr" where OP
1231   ** is an operator that gets passed into virtual tables but which is
1232   ** not normally optimized for ordinary tables.  In other words, OP
1233   ** is one of MATCH, LIKE, GLOB, REGEXP, !=, IS, IS NOT, or NOT NULL.
1234   ** This information is used by the xBestIndex methods of
1235   ** virtual tables.  The native query optimizer does not attempt
1236   ** to do anything with MATCH functions.
1237   */
1238   if( pWC->op==TK_AND ){
1239     Expr *pRight = 0, *pLeft = 0;
1240     int res = isAuxiliaryVtabOperator(pExpr, &eOp2, &pLeft, &pRight);
1241     while( res-- > 0 ){
1242       int idxNew;
1243       WhereTerm *pNewTerm;
1244       Bitmask prereqColumn, prereqExpr;
1245
1246       prereqExpr = sqlite3WhereExprUsage(pMaskSet, pRight);
1247       prereqColumn = sqlite3WhereExprUsage(pMaskSet, pLeft);
1248       if( (prereqExpr & prereqColumn)==0 ){
1249         Expr *pNewExpr;
1250         pNewExpr = sqlite3PExpr(pParse, TK_MATCH,
1251             0, sqlite3ExprDup(db, pRight, 0));
1252         if( ExprHasProperty(pExpr, EP_FromJoin) && pNewExpr ){
1253           ExprSetProperty(pNewExpr, EP_FromJoin);
1254         }
1255         idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
1256         testcase( idxNew==0 );
1257         pNewTerm = &pWC->a[idxNew];
1258         pNewTerm->prereqRight = prereqExpr;
1259         pNewTerm->leftCursor = pLeft->iTable;
1260         pNewTerm->u.leftColumn = pLeft->iColumn;
1261         pNewTerm->eOperator = WO_AUX;
1262         pNewTerm->eMatchOp = eOp2;
1263         markTermAsChild(pWC, idxNew, idxTerm);
1264         pTerm = &pWC->a[idxTerm];
1265         pTerm->wtFlags |= TERM_COPIED;
1266         pNewTerm->prereqAll = pTerm->prereqAll;
1267       }
1268       SWAP(Expr*, pLeft, pRight);
1269     }
1270   }
1271 #endif /* SQLITE_OMIT_VIRTUALTABLE */
1272
1273   /* If there is a vector == or IS term - e.g. "(a, b) == (?, ?)" - create
1274   ** new terms for each component comparison - "a = ?" and "b = ?".  The
1275   ** new terms completely replace the original vector comparison, which is
1276   ** no longer used.
1277   **
1278   ** This is only required if at least one side of the comparison operation
1279   ** is not a sub-select.  */
1280   if( pWC->op==TK_AND
1281   && (pExpr->op==TK_EQ || pExpr->op==TK_IS)
1282   && (nLeft = sqlite3ExprVectorSize(pExpr->pLeft))>1
1283   && sqlite3ExprVectorSize(pExpr->pRight)==nLeft
1284   && ( (pExpr->pLeft->flags & EP_xIsSelect)==0
1285     || (pExpr->pRight->flags & EP_xIsSelect)==0)
1286   ){
1287     int i;
1288     for(i=0; i<nLeft; i++){
1289       int idxNew;
1290       Expr *pNew;
1291       Expr *pLeft = sqlite3ExprForVectorField(pParse, pExpr->pLeft, i);
1292       Expr *pRight = sqlite3ExprForVectorField(pParse, pExpr->pRight, i);
1293
1294       pNew = sqlite3PExpr(pParse, pExpr->op, pLeft, pRight);
1295       transferJoinMarkings(pNew, pExpr);
1296       idxNew = whereClauseInsert(pWC, pNew, TERM_DYNAMIC);
1297       exprAnalyze(pSrc, pWC, idxNew);
1298     }
1299     pTerm = &pWC->a[idxTerm];
1300     pTerm->wtFlags |= TERM_CODED|TERM_VIRTUAL;  /* Disable the original */
1301     pTerm->eOperator = 0;
1302   }
1303
1304   /* If there is a vector IN term - e.g. "(a, b) IN (SELECT ...)" - create
1305   ** a virtual term for each vector component. The expression object
1306   ** used by each such virtual term is pExpr (the full vector IN(...)
1307   ** expression). The WhereTerm.iField variable identifies the index within
1308   ** the vector on the LHS that the virtual term represents.
1309   **
1310   ** This only works if the RHS is a simple SELECT, not a compound
1311   */
1312   if( pWC->op==TK_AND && pExpr->op==TK_IN && pTerm->iField==0
1313    && pExpr->pLeft->op==TK_VECTOR
1314    && pExpr->x.pSelect->pPrior==0
1315   ){
1316     int i;
1317     for(i=0; i<sqlite3ExprVectorSize(pExpr->pLeft); i++){
1318       int idxNew;
1319       idxNew = whereClauseInsert(pWC, pExpr, TERM_VIRTUAL);
1320       pWC->a[idxNew].iField = i+1;
1321       exprAnalyze(pSrc, pWC, idxNew);
1322       markTermAsChild(pWC, idxNew, idxTerm);
1323     }
1324   }
1325
1326 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
1327   /* When sqlite_stat3 histogram data is available an operator of the
1328   ** form "x IS NOT NULL" can sometimes be evaluated more efficiently
1329   ** as "x>NULL" if x is not an INTEGER PRIMARY KEY.  So construct a
1330   ** virtual term of that form.
1331   **
1332   ** Note that the virtual term must be tagged with TERM_VNULL.
1333   */
1334   if( pExpr->op==TK_NOTNULL
1335    && pExpr->pLeft->op==TK_COLUMN
1336    && pExpr->pLeft->iColumn>=0
1337    && OptimizationEnabled(db, SQLITE_Stat34)
1338   ){
1339     Expr *pNewExpr;
1340     Expr *pLeft = pExpr->pLeft;
1341     int idxNew;
1342     WhereTerm *pNewTerm;
1343
1344     pNewExpr = sqlite3PExpr(pParse, TK_GT,
1345                             sqlite3ExprDup(db, pLeft, 0),
1346                             sqlite3ExprAlloc(db, TK_NULL, 0, 0));
1347
1348     idxNew = whereClauseInsert(pWC, pNewExpr,
1349                               TERM_VIRTUAL|TERM_DYNAMIC|TERM_VNULL);
1350     if( idxNew ){
1351       pNewTerm = &pWC->a[idxNew];
1352       pNewTerm->prereqRight = 0;
1353       pNewTerm->leftCursor = pLeft->iTable;
1354       pNewTerm->u.leftColumn = pLeft->iColumn;
1355       pNewTerm->eOperator = WO_GT;
1356       markTermAsChild(pWC, idxNew, idxTerm);
1357       pTerm = &pWC->a[idxTerm];
1358       pTerm->wtFlags |= TERM_COPIED;
1359       pNewTerm->prereqAll = pTerm->prereqAll;
1360     }
1361   }
1362 #endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
1363
1364   /* Prevent ON clause terms of a LEFT JOIN from being used to drive
1365   ** an index for tables to the left of the join.
1366   */
1367   testcase( pTerm!=&pWC->a[idxTerm] );
1368   pTerm = &pWC->a[idxTerm];
1369   pTerm->prereqRight |= extraRight;
1370 }
1371
1372 /***************************************************************************
1373 ** Routines with file scope above.  Interface to the rest of the where.c
1374 ** subsystem follows.
1375 ***************************************************************************/
1376
1377 /*
1378 ** This routine identifies subexpressions in the WHERE clause where
1379 ** each subexpression is separated by the AND operator or some other
1380 ** operator specified in the op parameter.  The WhereClause structure
1381 ** is filled with pointers to subexpressions.  For example:
1382 **
1383 **    WHERE  a=='hello' AND coalesce(b,11)<10 AND (c+12!=d OR c==22)
1384 **           \________/     \_______________/     \________________/
1385 **            slot[0]            slot[1]               slot[2]
1386 **
1387 ** The original WHERE clause in pExpr is unaltered.  All this routine
1388 ** does is make slot[] entries point to substructure within pExpr.
1389 **
1390 ** In the previous sentence and in the diagram, "slot[]" refers to
1391 ** the WhereClause.a[] array.  The slot[] array grows as needed to contain
1392 ** all terms of the WHERE clause.
1393 */
1394 void sqlite3WhereSplit(WhereClause *pWC, Expr *pExpr, u8 op){
1395   Expr *pE2 = sqlite3ExprSkipCollate(pExpr);
1396   pWC->op = op;
1397   if( pE2==0 ) return;
1398   if( pE2->op!=op ){
1399     whereClauseInsert(pWC, pExpr, 0);
1400   }else{
1401     sqlite3WhereSplit(pWC, pE2->pLeft, op);
1402     sqlite3WhereSplit(pWC, pE2->pRight, op);
1403   }
1404 }
1405
1406 /*
1407 ** Initialize a preallocated WhereClause structure.
1408 */
1409 void sqlite3WhereClauseInit(
1410   WhereClause *pWC,        /* The WhereClause to be initialized */
1411   WhereInfo *pWInfo        /* The WHERE processing context */
1412 ){
1413   pWC->pWInfo = pWInfo;
1414   pWC->hasOr = 0;
1415   pWC->pOuter = 0;
1416   pWC->nTerm = 0;
1417   pWC->nSlot = ArraySize(pWC->aStatic);
1418   pWC->a = pWC->aStatic;
1419 }
1420
1421 /*
1422 ** Deallocate a WhereClause structure.  The WhereClause structure
1423 ** itself is not freed.  This routine is the inverse of
1424 ** sqlite3WhereClauseInit().
1425 */
1426 void sqlite3WhereClauseClear(WhereClause *pWC){
1427   int i;
1428   WhereTerm *a;
1429   sqlite3 *db = pWC->pWInfo->pParse->db;
1430   for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){
1431     if( a->wtFlags & TERM_DYNAMIC ){
1432       sqlite3ExprDelete(db, a->pExpr);
1433     }
1434     if( a->wtFlags & TERM_ORINFO ){
1435       whereOrInfoDelete(db, a->u.pOrInfo);
1436     }else if( a->wtFlags & TERM_ANDINFO ){
1437       whereAndInfoDelete(db, a->u.pAndInfo);
1438     }
1439   }
1440   if( pWC->a!=pWC->aStatic ){
1441     sqlite3DbFree(db, pWC->a);
1442   }
1443 }
1444
1445
1446 /*
1447 ** These routines walk (recursively) an expression tree and generate
1448 ** a bitmask indicating which tables are used in that expression
1449 ** tree.
1450 */
1451 Bitmask sqlite3WhereExprUsageNN(WhereMaskSet *pMaskSet, Expr *p){
1452   Bitmask mask;
1453   if( p->op==TK_COLUMN ){
1454     return sqlite3WhereGetMask(pMaskSet, p->iTable);
1455   }else if( ExprHasProperty(p, EP_TokenOnly|EP_Leaf) ){
1456     assert( p->op!=TK_IF_NULL_ROW );
1457     return 0;
1458   }
1459   mask = (p->op==TK_IF_NULL_ROW) ? sqlite3WhereGetMask(pMaskSet, p->iTable) : 0;
1460   if( p->pLeft ) mask |= sqlite3WhereExprUsageNN(pMaskSet, p->pLeft);
1461   if( p->pRight ){
1462     mask |= sqlite3WhereExprUsageNN(pMaskSet, p->pRight);
1463     assert( p->x.pList==0 );
1464   }else if( ExprHasProperty(p, EP_xIsSelect) ){
1465     if( ExprHasProperty(p, EP_VarSelect) ) pMaskSet->bVarSelect = 1;
1466     mask |= exprSelectUsage(pMaskSet, p->x.pSelect);
1467   }else if( p->x.pList ){
1468     mask |= sqlite3WhereExprListUsage(pMaskSet, p->x.pList);
1469   }
1470   return mask;
1471 }
1472 Bitmask sqlite3WhereExprUsage(WhereMaskSet *pMaskSet, Expr *p){
1473   return p ? sqlite3WhereExprUsageNN(pMaskSet,p) : 0;
1474 }
1475 Bitmask sqlite3WhereExprListUsage(WhereMaskSet *pMaskSet, ExprList *pList){
1476   int i;
1477   Bitmask mask = 0;
1478   if( pList ){
1479     for(i=0; i<pList->nExpr; i++){
1480       mask |= sqlite3WhereExprUsage(pMaskSet, pList->a[i].pExpr);
1481     }
1482   }
1483   return mask;
1484 }
1485
1486
1487 /*
1488 ** Call exprAnalyze on all terms in a WHERE clause.
1489 **
1490 ** Note that exprAnalyze() might add new virtual terms onto the
1491 ** end of the WHERE clause.  We do not want to analyze these new
1492 ** virtual terms, so start analyzing at the end and work forward
1493 ** so that the added virtual terms are never processed.
1494 */
1495 void sqlite3WhereExprAnalyze(
1496   SrcList *pTabList,       /* the FROM clause */
1497   WhereClause *pWC         /* the WHERE clause to be analyzed */
1498 ){
1499   int i;
1500   for(i=pWC->nTerm-1; i>=0; i--){
1501     exprAnalyze(pTabList, pWC, i);
1502   }
1503 }
1504
1505 /*
1506 ** For table-valued-functions, transform the function arguments into
1507 ** new WHERE clause terms.
1508 **
1509 ** Each function argument translates into an equality constraint against
1510 ** a HIDDEN column in the table.
1511 */
1512 void sqlite3WhereTabFuncArgs(
1513   Parse *pParse,                    /* Parsing context */
1514   struct SrcList_item *pItem,       /* The FROM clause term to process */
1515   WhereClause *pWC                  /* Xfer function arguments to here */
1516 ){
1517   Table *pTab;
1518   int j, k;
1519   ExprList *pArgs;
1520   Expr *pColRef;
1521   Expr *pTerm;
1522   if( pItem->fg.isTabFunc==0 ) return;
1523   pTab = pItem->pTab;
1524   assert( pTab!=0 );
1525   pArgs = pItem->u1.pFuncArg;
1526   if( pArgs==0 ) return;
1527   for(j=k=0; j<pArgs->nExpr; j++){
1528     while( k<pTab->nCol && (pTab->aCol[k].colFlags & COLFLAG_HIDDEN)==0 ){k++;}
1529     if( k>=pTab->nCol ){
1530       sqlite3ErrorMsg(pParse, "too many arguments on %s() - max %d",
1531                       pTab->zName, j);
1532       return;
1533     }
1534     pColRef = sqlite3ExprAlloc(pParse->db, TK_COLUMN, 0, 0);
1535     if( pColRef==0 ) return;
1536     pColRef->iTable = pItem->iCursor;
1537     pColRef->iColumn = k++;
1538     pColRef->pTab = pTab;
1539     pTerm = sqlite3PExpr(pParse, TK_EQ, pColRef,
1540                          sqlite3ExprDup(pParse->db, pArgs->a[j].pExpr, 0));
1541     whereClauseInsert(pWC, pTerm, TERM_DYNAMIC);
1542   }
1543 }