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/*
** 2015-06-08
**
** The author disclaims copyright to this source code. In place of
** a legal notice, here is a blessing:
**
** May you do good and not evil.
** May you find forgiveness for yourself and forgive others.
** May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.
**
** This file was originally part of where.c but was split out to improve
** readability and editabiliity. This file contains utility routines for
** analyzing Expr objects in the WHERE clause.
*/
#include "sqliteInt.h"
#include "whereInt.h"
/* Forward declarations */
static void exprAnalyze(SrcList*, WhereClause*, int);
/*
** Deallocate all memory associated with a WhereOrInfo object.
*/
static void whereOrInfoDelete(sqlite3 *db, WhereOrInfo *p){
sqlite3WhereClauseClear(&p->wc);
sqlite3DbFree(db, p);
}
/*
** Deallocate all memory associated with a WhereAndInfo object.
*/
static void whereAndInfoDelete(sqlite3 *db, WhereAndInfo *p){
sqlite3WhereClauseClear(&p->wc);
sqlite3DbFree(db, p);
}
/*
** Add a single new WhereTerm entry to the WhereClause object pWC.
** The new WhereTerm object is constructed from Expr p and with wtFlags.
** The index in pWC->a[] of the new WhereTerm is returned on success.
** 0 is returned if the new WhereTerm could not be added due to a memory
** allocation error. The memory allocation failure will be recorded in
** the db->mallocFailed flag so that higher-level functions can detect it.
**
** This routine will increase the size of the pWC->a[] array as necessary.
**
** If the wtFlags argument includes TERM_DYNAMIC, then responsibility
** for freeing the expression p is assumed by the WhereClause object pWC.
** This is true even if this routine fails to allocate a new WhereTerm.
**
** WARNING: This routine might reallocate the space used to store
** WhereTerms. All pointers to WhereTerms should be invalidated after
** calling this routine. Such pointers may be reinitialized by referencing
** the pWC->a[] array.
*/
static int whereClauseInsert(WhereClause *pWC, Expr *p, u16 wtFlags){
WhereTerm *pTerm;
int idx;
testcase( wtFlags & TERM_VIRTUAL );
if( pWC->nTerm>=pWC->nSlot ){
WhereTerm *pOld = pWC->a;
sqlite3 *db = pWC->pWInfo->pParse->db;
pWC->a = sqlite3DbMallocRawNN(db, sizeof(pWC->a[0])*pWC->nSlot*2 );
if( pWC->a==0 ){
if( wtFlags & TERM_DYNAMIC ){
sqlite3ExprDelete(db, p);
}
pWC->a = pOld;
return 0;
}
memcpy(pWC->a, pOld, sizeof(pWC->a[0])*pWC->nTerm);
if( pOld!=pWC->aStatic ){
sqlite3DbFree(db, pOld);
}
pWC->nSlot = sqlite3DbMallocSize(db, pWC->a)/sizeof(pWC->a[0]);
}
pTerm = &pWC->a[idx = pWC->nTerm++];
if( p && ExprHasProperty(p, EP_Unlikely) ){
pTerm->truthProb = sqlite3LogEst(p->iTable) - 270;
}else{
pTerm->truthProb = 1;
}
pTerm->pExpr = sqlite3ExprSkipCollateAndLikely(p);
pTerm->wtFlags = wtFlags;
pTerm->pWC = pWC;
pTerm->iParent = -1;
memset(&pTerm->eOperator, 0,
sizeof(WhereTerm) - offsetof(WhereTerm,eOperator));
return idx;
}
/*
** Return TRUE if the given operator is one of the operators that is
** allowed for an indexable WHERE clause term. The allowed operators are
** "=", "<", ">", "<=", ">=", "IN", "IS", and "IS NULL"
*/
static int allowedOp(int op){
assert( TK_GT>TK_EQ && TK_GT<TK_GE );
assert( TK_LT>TK_EQ && TK_LT<TK_GE );
assert( TK_LE>TK_EQ && TK_LE<TK_GE );
assert( TK_GE==TK_EQ+4 );
return op==TK_IN || (op>=TK_EQ && op<=TK_GE) || op==TK_ISNULL || op==TK_IS;
}
/*
** Commute a comparison operator. Expressions of the form "X op Y"
** are converted into "Y op X".
**
** If left/right precedence rules come into play when determining the
** collating sequence, then COLLATE operators are adjusted to ensure
** that the collating sequence does not change. For example:
** "Y collate NOCASE op X" becomes "X op Y" because any collation sequence on
** the left hand side of a comparison overrides any collation sequence
** attached to the right. For the same reason the EP_Collate flag
** is not commuted.
**
** The return value is extra flags that are added to the WhereTerm object
** after it is commuted. The only extra flag ever added is TERM_NOPARTIDX
** which prevents the term from being used to enable a partial index if
** COLLATE changes have been made.
*/
static u16 exprCommute(Parse *pParse, Expr *pExpr){
u16 expRight = (pExpr->pRight->flags & EP_Collate);
u16 expLeft = (pExpr->pLeft->flags & EP_Collate);
u16 wtFlags = 0;
assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN );
if( expRight==expLeft ){
/* Either X and Y both have COLLATE operator or neither do */
if( expRight ){
/* Both X and Y have COLLATE operators. Make sure X is always
** used by clearing the EP_Collate flag from Y. */
pExpr->pRight->flags &= ~EP_Collate;
wtFlags |= TERM_NOPARTIDX;
}else if( sqlite3ExprCollSeq(pParse, pExpr->pLeft)!=0 ){
/* Neither X nor Y have COLLATE operators, but X has a non-default
** collating sequence. So add the EP_Collate marker on X to cause
** it to be searched first. */
pExpr->pLeft->flags |= EP_Collate;
wtFlags |= TERM_NOPARTIDX;
}
}
SWAP(Expr*,pExpr->pRight,pExpr->pLeft);
if( pExpr->op>=TK_GT ){
assert( TK_LT==TK_GT+2 );
assert( TK_GE==TK_LE+2 );
assert( TK_GT>TK_EQ );
assert( TK_GT<TK_LE );
assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE );
pExpr->op = ((pExpr->op-TK_GT)^2)+TK_GT;
}
return wtFlags;
}
/*
** Translate from TK_xx operator to WO_xx bitmask.
*/
static u16 operatorMask(int op){
u16 c;
assert( allowedOp(op) );
if( op==TK_IN ){
c = WO_IN;
}else if( op==TK_ISNULL ){
c = WO_ISNULL;
}else if( op==TK_IS ){
c = WO_IS;
}else{
assert( (WO_EQ<<(op-TK_EQ)) < 0x7fff );
c = (u16)(WO_EQ<<(op-TK_EQ));
}
assert( op!=TK_ISNULL || c==WO_ISNULL );
assert( op!=TK_IN || c==WO_IN );
assert( op!=TK_EQ || c==WO_EQ );
assert( op!=TK_LT || c==WO_LT );
assert( op!=TK_LE || c==WO_LE );
assert( op!=TK_GT || c==WO_GT );
assert( op!=TK_GE || c==WO_GE );
assert( op!=TK_IS || c==WO_IS );
return c;
}
#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
/*
** Check to see if the given expression is a LIKE or GLOB operator that
** can be optimized using inequality constraints. Return TRUE if it is
** so and false if not.
**
** In order for the operator to be optimizible, the RHS must be a string
** literal that does not begin with a wildcard. The LHS must be a column
** that may only be NULL, a string, or a BLOB, never a number. (This means
** that virtual tables cannot participate in the LIKE optimization.) The
** collating sequence for the column on the LHS must be appropriate for
** the operator.
*/
static int isLikeOrGlob(
Parse *pParse, /* Parsing and code generating context */
Expr *pExpr, /* Test this expression */
Expr **ppPrefix, /* Pointer to TK_STRING expression with pattern prefix */
int *pisComplete, /* True if the only wildcard is % in the last character */
int *pnoCase /* True if uppercase is equivalent to lowercase */
){
const u8 *z = 0; /* String on RHS of LIKE operator */
Expr *pRight, *pLeft; /* Right and left size of LIKE operator */
ExprList *pList; /* List of operands to the LIKE operator */
u8 c; /* One character in z[] */
int cnt; /* Number of non-wildcard prefix characters */
u8 wc[4]; /* Wildcard characters */
sqlite3 *db = pParse->db; /* Database connection */
sqlite3_value *pVal = 0;
int op; /* Opcode of pRight */
int rc; /* Result code to return */
if( !sqlite3IsLikeFunction(db, pExpr, pnoCase, (char*)wc) ){
return 0;
}
#ifdef SQLITE_EBCDIC
if( *pnoCase ) return 0;
#endif
pList = pExpr->x.pList;
pLeft = pList->a[1].pExpr;
pRight = sqlite3ExprSkipCollate(pList->a[0].pExpr);
op = pRight->op;
if( op==TK_VARIABLE && (db->flags & SQLITE_EnableQPSG)==0 ){
Vdbe *pReprepare = pParse->pReprepare;
int iCol = pRight->iColumn;
pVal = sqlite3VdbeGetBoundValue(pReprepare, iCol, SQLITE_AFF_BLOB);
if( pVal && sqlite3_value_type(pVal)==SQLITE_TEXT ){
z = sqlite3_value_text(pVal);
}
sqlite3VdbeSetVarmask(pParse->pVdbe, iCol);
assert( pRight->op==TK_VARIABLE || pRight->op==TK_REGISTER );
}else if( op==TK_STRING ){
z = (u8*)pRight->u.zToken;
}
if( z ){
/* Count the number of prefix characters prior to the first wildcard */
cnt = 0;
while( (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2] ){
cnt++;
if( c==wc[3] && z[cnt]!=0 ) cnt++;
}
/* The optimization is possible only if (1) the pattern does not begin
** with a wildcard and if (2) the non-wildcard prefix does not end with
** an (illegal 0xff) character, or (3) the pattern does not consist of
** a single escape character. The second condition is necessary so
** that we can increment the prefix key to find an upper bound for the
** range search. The third is because the caller assumes that the pattern
** consists of at least one character after all escapes have been
** removed. */
if( cnt!=0 && 255!=(u8)z[cnt-1] && (cnt>1 || z[0]!=wc[3]) ){
Expr *pPrefix;
/* A "complete" match if the pattern ends with "*" or "%" */
*pisComplete = c==wc[0] && z[cnt+1]==0;
/* Get the pattern prefix. Remove all escapes from the prefix. */
pPrefix = sqlite3Expr(db, TK_STRING, (char*)z);
if( pPrefix ){
int iFrom, iTo;
char *zNew = pPrefix->u.zToken;
zNew[cnt] = 0;
for(iFrom=iTo=0; iFrom<cnt; iFrom++){
if( zNew[iFrom]==wc[3] ) iFrom++;
zNew[iTo++] = zNew[iFrom];
}
zNew[iTo] = 0;
assert( iTo>0 );
/* If the LHS is not an ordinary column with TEXT affinity, then the
** pattern prefix boundaries (both the start and end boundaries) must
** not look like a number. Otherwise the pattern might be treated as
** a number, which will invalidate the LIKE optimization.
**
** Getting this right has been a persistent source of bugs in the
** LIKE optimization. See, for example:
** 2018-09-10 https://sqlite.org/src/info/c94369cae9b561b1
** 2019-05-02 https://sqlite.org/src/info/b043a54c3de54b28
** 2019-06-10 https://sqlite.org/src/info/fd76310a5e843e07
** 2019-06-14 https://sqlite.org/src/info/ce8717f0885af975
** 2019-09-03 https://sqlite.org/src/info/0f0428096f17252a
*/
if( pLeft->op!=TK_COLUMN
|| sqlite3ExprAffinity(pLeft)!=SQLITE_AFF_TEXT
|| IsVirtual(pLeft->y.pTab) /* Value might be numeric */
){
int isNum;
double rDummy;
isNum = sqlite3AtoF(zNew, &rDummy, iTo, SQLITE_UTF8);
if( isNum<=0 ){
if( iTo==1 && zNew[0]=='-' ){
isNum = +1;
}else{
zNew[iTo-1]++;
isNum = sqlite3AtoF(zNew, &rDummy, iTo, SQLITE_UTF8);
zNew[iTo-1]--;
}
}
if( isNum>0 ){
sqlite3ExprDelete(db, pPrefix);
sqlite3ValueFree(pVal);
return 0;
}
}
}
*ppPrefix = pPrefix;
/* If the RHS pattern is a bound parameter, make arrangements to
** reprepare the statement when that parameter is rebound */
if( op==TK_VARIABLE ){
Vdbe *v = pParse->pVdbe;
sqlite3VdbeSetVarmask(v, pRight->iColumn);
if( *pisComplete && pRight->u.zToken[1] ){
/* If the rhs of the LIKE expression is a variable, and the current
** value of the variable means there is no need to invoke the LIKE
** function, then no OP_Variable will be added to the program.
** This causes problems for the sqlite3_bind_parameter_name()
** API. To work around them, add a dummy OP_Variable here.
*/
int r1 = sqlite3GetTempReg(pParse);
sqlite3ExprCodeTarget(pParse, pRight, r1);
sqlite3VdbeChangeP3(v, sqlite3VdbeCurrentAddr(v)-1, 0);
sqlite3ReleaseTempReg(pParse, r1);
}
}
}else{
z = 0;
}
}
rc = (z!=0);
sqlite3ValueFree(pVal);
return rc;
}
#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
#ifndef SQLITE_OMIT_VIRTUALTABLE
/*
** Check to see if the pExpr expression is a form that needs to be passed
** to the xBestIndex method of virtual tables. Forms of interest include:
**
** Expression Virtual Table Operator
** ----------------------- ---------------------------------
** 1. column MATCH expr SQLITE_INDEX_CONSTRAINT_MATCH
** 2. column GLOB expr SQLITE_INDEX_CONSTRAINT_GLOB
** 3. column LIKE expr SQLITE_INDEX_CONSTRAINT_LIKE
** 4. column REGEXP expr SQLITE_INDEX_CONSTRAINT_REGEXP
** 5. column != expr SQLITE_INDEX_CONSTRAINT_NE
** 6. expr != column SQLITE_INDEX_CONSTRAINT_NE
** 7. column IS NOT expr SQLITE_INDEX_CONSTRAINT_ISNOT
** 8. expr IS NOT column SQLITE_INDEX_CONSTRAINT_ISNOT
** 9. column IS NOT NULL SQLITE_INDEX_CONSTRAINT_ISNOTNULL
**
** In every case, "column" must be a column of a virtual table. If there
** is a match, set *ppLeft to the "column" expression, set *ppRight to the
** "expr" expression (even though in forms (6) and (8) the column is on the
** right and the expression is on the left). Also set *peOp2 to the
** appropriate virtual table operator. The return value is 1 or 2 if there
** is a match. The usual return is 1, but if the RHS is also a column
** of virtual table in forms (5) or (7) then return 2.
**
** If the expression matches none of the patterns above, return 0.
*/
static int isAuxiliaryVtabOperator(
sqlite3 *db, /* Parsing context */
Expr *pExpr, /* Test this expression */
unsigned char *peOp2, /* OUT: 0 for MATCH, or else an op2 value */
Expr **ppLeft, /* Column expression to left of MATCH/op2 */
Expr **ppRight /* Expression to left of MATCH/op2 */
){
if( pExpr->op==TK_FUNCTION ){
static const struct Op2 {
const char *zOp;
unsigned char eOp2;
} aOp[] = {
{ "match", SQLITE_INDEX_CONSTRAINT_MATCH },
{ "glob", SQLITE_INDEX_CONSTRAINT_GLOB },
{ "like", SQLITE_INDEX_CONSTRAINT_LIKE },
{ "regexp", SQLITE_INDEX_CONSTRAINT_REGEXP }
};
ExprList *pList;
Expr *pCol; /* Column reference */
int i;
pList = pExpr->x.pList;
if( pList==0 || pList->nExpr!=2 ){
return 0;
}
/* Built-in operators MATCH, GLOB, LIKE, and REGEXP attach to a
** virtual table on their second argument, which is the same as
** the left-hand side operand in their in-fix form.
**
** vtab_column MATCH expression
** MATCH(expression,vtab_column)
*/
pCol = pList->a[1].pExpr;
if( pCol->op==TK_COLUMN && IsVirtual(pCol->y.pTab) ){
for(i=0; i<ArraySize(aOp); i++){
if( sqlite3StrICmp(pExpr->u.zToken, aOp[i].zOp)==0 ){
*peOp2 = aOp[i].eOp2;
*ppRight = pList->a[0].pExpr;
*ppLeft = pCol;
return 1;
}
}
}
/* We can also match against the first column of overloaded
** functions where xFindFunction returns a value of at least
** SQLITE_INDEX_CONSTRAINT_FUNCTION.
**
** OVERLOADED(vtab_column,expression)
**
** Historically, xFindFunction expected to see lower-case function
** names. But for this use case, xFindFunction is expected to deal
** with function names in an arbitrary case.
*/
pCol = pList->a[0].pExpr;
if( pCol->op==TK_COLUMN && IsVirtual(pCol->y.pTab) ){
sqlite3_vtab *pVtab;
sqlite3_module *pMod;
void (*xNotUsed)(sqlite3_context*,int,sqlite3_value**);
void *pNotUsed;
pVtab = sqlite3GetVTable(db, pCol->y.pTab)->pVtab;
assert( pVtab!=0 );
assert( pVtab->pModule!=0 );
pMod = (sqlite3_module *)pVtab->pModule;
if( pMod->xFindFunction!=0 ){
i = pMod->xFindFunction(pVtab,2, pExpr->u.zToken, &xNotUsed, &pNotUsed);
if( i>=SQLITE_INDEX_CONSTRAINT_FUNCTION ){
*peOp2 = i;
*ppRight = pList->a[1].pExpr;
*ppLeft = pCol;
return 1;
}
}
}
}else if( pExpr->op==TK_NE || pExpr->op==TK_ISNOT || pExpr->op==TK_NOTNULL ){
int res = 0;
Expr *pLeft = pExpr->pLeft;
Expr *pRight = pExpr->pRight;
if( pLeft->op==TK_COLUMN && IsVirtual(pLeft->y.pTab) ){
res++;
}
if( pRight && pRight->op==TK_COLUMN && IsVirtual(pRight->y.pTab) ){
res++;
SWAP(Expr*, pLeft, pRight);
}
*ppLeft = pLeft;
*ppRight = pRight;
if( pExpr->op==TK_NE ) *peOp2 = SQLITE_INDEX_CONSTRAINT_NE;
if( pExpr->op==TK_ISNOT ) *peOp2 = SQLITE_INDEX_CONSTRAINT_ISNOT;
if( pExpr->op==TK_NOTNULL ) *peOp2 = SQLITE_INDEX_CONSTRAINT_ISNOTNULL;
return res;
}
return 0;
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */
/*
** If the pBase expression originated in the ON or USING clause of
** a join, then transfer the appropriate markings over to derived.
*/
static void transferJoinMarkings(Expr *pDerived, Expr *pBase){
if( pDerived ){
pDerived->flags |= pBase->flags & EP_FromJoin;
pDerived->iRightJoinTable = pBase->iRightJoinTable;
}
}
/*
** Mark term iChild as being a child of term iParent
*/
static void markTermAsChild(WhereClause *pWC, int iChild, int iParent){
pWC->a[iChild].iParent = iParent;
pWC->a[iChild].truthProb = pWC->a[iParent].truthProb;
pWC->a[iParent].nChild++;
}
/*
** Return the N-th AND-connected subterm of pTerm. Or if pTerm is not
** a conjunction, then return just pTerm when N==0. If N is exceeds
** the number of available subterms, return NULL.
*/
static WhereTerm *whereNthSubterm(WhereTerm *pTerm, int N){
if( pTerm->eOperator!=WO_AND ){
return N==0 ? pTerm : 0;
}
if( N<pTerm->u.pAndInfo->wc.nTerm ){
return &pTerm->u.pAndInfo->wc.a[N];
}
return 0;
}
/*
** Subterms pOne and pTwo are contained within WHERE clause pWC. The
** two subterms are in disjunction - they are OR-ed together.
**
** If these two terms are both of the form: "A op B" with the same
** A and B values but different operators and if the operators are
** compatible (if one is = and the other is <, for example) then
** add a new virtual AND term to pWC that is the combination of the
** two.
**
** Some examples:
**
** x<y OR x=y --> x<=y
** x=y OR x=y --> x=y
** x<=y OR x<y --> x<=y
**
** The following is NOT generated:
**
** x<y OR x>y --> x!=y
*/
static void whereCombineDisjuncts(
SrcList *pSrc, /* the FROM clause */
WhereClause *pWC, /* The complete WHERE clause */
WhereTerm *pOne, /* First disjunct */
WhereTerm *pTwo /* Second disjunct */
){
u16 eOp = pOne->eOperator | pTwo->eOperator;
sqlite3 *db; /* Database connection (for malloc) */
Expr *pNew; /* New virtual expression */
int op; /* Operator for the combined expression */
int idxNew; /* Index in pWC of the next virtual term */
if( (pOne->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return;
if( (pTwo->eOperator & (WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE))==0 ) return;
if( (eOp & (WO_EQ|WO_LT|WO_LE))!=eOp
&& (eOp & (WO_EQ|WO_GT|WO_GE))!=eOp ) return;
assert( pOne->pExpr->pLeft!=0 && pOne->pExpr->pRight!=0 );
assert( pTwo->pExpr->pLeft!=0 && pTwo->pExpr->pRight!=0 );
if( sqlite3ExprCompare(0,pOne->pExpr->pLeft, pTwo->pExpr->pLeft, -1) ) return;
if( sqlite3ExprCompare(0,pOne->pExpr->pRight, pTwo->pExpr->pRight,-1) )return;
/* If we reach this point, it means the two subterms can be combined */
if( (eOp & (eOp-1))!=0 ){
if( eOp & (WO_LT|WO_LE) ){
eOp = WO_LE;
}else{
assert( eOp & (WO_GT|WO_GE) );
eOp = WO_GE;
}
}
db = pWC->pWInfo->pParse->db;
pNew = sqlite3ExprDup(db, pOne->pExpr, 0);
if( pNew==0 ) return;
for(op=TK_EQ; eOp!=(WO_EQ<<(op-TK_EQ)); op++){ assert( op<TK_GE ); }
pNew->op = op;
idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC);
exprAnalyze(pSrc, pWC, idxNew);
}
#if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
/*
** Analyze a term that consists of two or more OR-connected
** subterms. So in:
**
** ... WHERE (a=5) AND (b=7 OR c=9 OR d=13) AND (d=13)
** ^^^^^^^^^^^^^^^^^^^^
**
** This routine analyzes terms such as the middle term in the above example.
** A WhereOrTerm object is computed and attached to the term under
** analysis, regardless of the outcome of the analysis. Hence:
**
** WhereTerm.wtFlags |= TERM_ORINFO
** WhereTerm.u.pOrInfo = a dynamically allocated WhereOrTerm object
**
** The term being analyzed must have two or more of OR-connected subterms.
** A single subterm might be a set of AND-connected sub-subterms.
** Examples of terms under analysis:
**
** (A) t1.x=t2.y OR t1.x=t2.z OR t1.y=15 OR t1.z=t3.a+5
** (B) x=expr1 OR expr2=x OR x=expr3
** (C) t1.x=t2.y OR (t1.x=t2.z AND t1.y=15)
** (D) x=expr1 OR (y>11 AND y<22 AND z LIKE '*hello*')
** (E) (p.a=1 AND q.b=2 AND r.c=3) OR (p.x=4 AND q.y=5 AND r.z=6)
** (F) x>A OR (x=A AND y>=B)
**
** CASE 1:
**
** If all subterms are of the form T.C=expr for some single column of C and
** a single table T (as shown in example B above) then create a new virtual
** term that is an equivalent IN expression. In other words, if the term
** being analyzed is:
**
** x = expr1 OR expr2 = x OR x = expr3
**
** then create a new virtual term like this:
**
** x IN (expr1,expr2,expr3)
**
** CASE 2:
**
** If there are exactly two disjuncts and one side has x>A and the other side
** has x=A (for the same x and A) then add a new virtual conjunct term to the
** WHERE clause of the form "x>=A". Example:
**
** x>A OR (x=A AND y>B) adds: x>=A
**
** The added conjunct can sometimes be helpful in query planning.
**
** CASE 3:
**
** If all subterms are indexable by a single table T, then set
**
** WhereTerm.eOperator = WO_OR
** WhereTerm.u.pOrInfo->indexable |= the cursor number for table T
**
** A subterm is "indexable" if it is of the form
** "T.C <op> <expr>" where C is any column of table T and
** <op> is one of "=", "<", "<=", ">", ">=", "IS NULL", or "IN".
** A subterm is also indexable if it is an AND of two or more
** subsubterms at least one of which is indexable. Indexable AND
** subterms have their eOperator set to WO_AND and they have
** u.pAndInfo set to a dynamically allocated WhereAndTerm object.
**
** From another point of view, "indexable" means that the subterm could
** potentially be used with an index if an appropriate index exists.
** This analysis does not consider whether or not the index exists; that
** is decided elsewhere. This analysis only looks at whether subterms
** appropriate for indexing exist.
**
** All examples A through E above satisfy case 3. But if a term
** also satisfies case 1 (such as B) we know that the optimizer will
** always prefer case 1, so in that case we pretend that case 3 is not
** satisfied.
**
** It might be the case that multiple tables are indexable. For example,
** (E) above is indexable on tables P, Q, and R.
**
** Terms that satisfy case 3 are candidates for lookup by using
** separate indices to find rowids for each subterm and composing
** the union of all rowids using a RowSet object. This is similar
** to "bitmap indices" in other database engines.
**
** OTHERWISE:
**
** If none of cases 1, 2, or 3 apply, then leave the eOperator set to
** zero. This term is not useful for search.
*/
static void exprAnalyzeOrTerm(
SrcList *pSrc, /* the FROM clause */
WhereClause *pWC, /* the complete WHERE clause */
int idxTerm /* Index of the OR-term to be analyzed */
){
WhereInfo *pWInfo = pWC->pWInfo; /* WHERE clause processing context */
Parse *pParse = pWInfo->pParse; /* Parser context */
sqlite3 *db = pParse->db; /* Database connection */
WhereTerm *pTerm = &pWC->a[idxTerm]; /* The term to be analyzed */
Expr *pExpr = pTerm->pExpr; /* The expression of the term */
int i; /* Loop counters */
WhereClause *pOrWc; /* Breakup of pTerm into subterms */
WhereTerm *pOrTerm; /* A Sub-term within the pOrWc */
WhereOrInfo *pOrInfo; /* Additional information associated with pTerm */
Bitmask chngToIN; /* Tables that might satisfy case 1 */
Bitmask indexable; /* Tables that are indexable, satisfying case 2 */
/*
** Break the OR clause into its separate subterms. The subterms are
** stored in a WhereClause structure containing within the WhereOrInfo
** object that is attached to the original OR clause term.
*/
assert( (pTerm->wtFlags & (TERM_DYNAMIC|TERM_ORINFO|TERM_ANDINFO))==0 );
assert( pExpr->op==TK_OR );
pTerm->u.pOrInfo = pOrInfo = sqlite3DbMallocZero(db, sizeof(*pOrInfo));
if( pOrInfo==0 ) return;
pTerm->wtFlags |= TERM_ORINFO;
pOrWc = &pOrInfo->wc;
memset(pOrWc->aStatic, 0, sizeof(pOrWc->aStatic));
sqlite3WhereClauseInit(pOrWc, pWInfo);
sqlite3WhereSplit(pOrWc, pExpr, TK_OR);
sqlite3WhereExprAnalyze(pSrc, pOrWc);
if( db->mallocFailed ) return;
assert( pOrWc->nTerm>=2 );
/*
** Compute the set of tables that might satisfy cases 1 or 3.
*/
indexable = ~(Bitmask)0;
chngToIN = ~(Bitmask)0;
for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0 && indexable; i--, pOrTerm++){
if( (pOrTerm->eOperator & WO_SINGLE)==0 ){
WhereAndInfo *pAndInfo;
assert( (pOrTerm->wtFlags & (TERM_ANDINFO|TERM_ORINFO))==0 );
chngToIN = 0;
pAndInfo = sqlite3DbMallocRawNN(db, sizeof(*pAndInfo));
if( pAndInfo ){
WhereClause *pAndWC;
WhereTerm *pAndTerm;
int j;
Bitmask b = 0;
pOrTerm->u.pAndInfo = pAndInfo;
pOrTerm->wtFlags |= TERM_ANDINFO;
pOrTerm->eOperator = WO_AND;
pAndWC = &pAndInfo->wc;
memset(pAndWC->aStatic, 0, sizeof(pAndWC->aStatic));
sqlite3WhereClauseInit(pAndWC, pWC->pWInfo);
sqlite3WhereSplit(pAndWC, pOrTerm->pExpr, TK_AND);
sqlite3WhereExprAnalyze(pSrc, pAndWC);
pAndWC->pOuter = pWC;
if( !db->mallocFailed ){
for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){
assert( pAndTerm->pExpr );
if( allowedOp(pAndTerm->pExpr->op)
|| pAndTerm->eOperator==WO_AUX
){
b |= sqlite3WhereGetMask(&pWInfo->sMaskSet, pAndTerm->leftCursor);
}
}
}
indexable &= b;
}
}else if( pOrTerm->wtFlags & TERM_COPIED ){
/* Skip this term for now. We revisit it when we process the
** corresponding TERM_VIRTUAL term */
}else{
Bitmask b;
b = sqlite3WhereGetMask(&pWInfo->sMaskSet, pOrTerm->leftCursor);
if( pOrTerm->wtFlags & TERM_VIRTUAL ){
WhereTerm *pOther = &pOrWc->a[pOrTerm->iParent];
b |= sqlite3WhereGetMask(&pWInfo->sMaskSet, pOther->leftCursor);
}
indexable &= b;
if( (pOrTerm->eOperator & WO_EQ)==0 ){
chngToIN = 0;
}else{
chngToIN &= b;
}
}
}
/*
** Record the set of tables that satisfy case 3. The set might be
** empty.
*/
pOrInfo->indexable = indexable;
if( indexable ){
pTerm->eOperator = WO_OR;
pWC->hasOr = 1;
}else{
pTerm->eOperator = WO_OR;
}
/* For a two-way OR, attempt to implementation case 2.
*/
if( indexable && pOrWc->nTerm==2 ){
int iOne = 0;
WhereTerm *pOne;
while( (pOne = whereNthSubterm(&pOrWc->a[0],iOne++))!=0 ){
int iTwo = 0;
WhereTerm *pTwo;
while( (pTwo = whereNthSubterm(&pOrWc->a[1],iTwo++))!=0 ){
whereCombineDisjuncts(pSrc, pWC, pOne, pTwo);
}
}
}
/*
** chngToIN holds a set of tables that *might* satisfy case 1. But
** we have to do some additional checking to see if case 1 really
** is satisfied.
**
** chngToIN will hold either 0, 1, or 2 bits. The 0-bit case means
** that there is no possibility of transforming the OR clause into an
** IN operator because one or more terms in the OR clause contain
** something other than == on a column in the single table. The 1-bit
** case means that every term of the OR clause is of the form
** "table.column=expr" for some single table. The one bit that is set
** will correspond to the common table. We still need to check to make
** sure the same column is used on all terms. The 2-bit case is when
** the all terms are of the form "table1.column=table2.column". It
** might be possible to form an IN operator with either table1.column
** or table2.column as the LHS if either is common to every term of
** the OR clause.
**
** Note that terms of the form "table.column1=table.column2" (the
** same table on both sizes of the ==) cannot be optimized.
*/
if( chngToIN ){
int okToChngToIN = 0; /* True if the conversion to IN is valid */
int iColumn = -1; /* Column index on lhs of IN operator */
int iCursor = -1; /* Table cursor common to all terms */
int j = 0; /* Loop counter */
/* Search for a table and column that appears on one side or the
** other of the == operator in every subterm. That table and column
** will be recorded in iCursor and iColumn. There might not be any
** such table and column. Set okToChngToIN if an appropriate table
** and column is found but leave okToChngToIN false if not found.
*/
for(j=0; j<2 && !okToChngToIN; j++){
Expr *pLeft = 0;
pOrTerm = pOrWc->a;
for(i=pOrWc->nTerm-1; i>=0; i--, pOrTerm++){
assert( pOrTerm->eOperator & WO_EQ );
pOrTerm->wtFlags &= ~TERM_OR_OK;
if( pOrTerm->leftCursor==iCursor ){
/* This is the 2-bit case and we are on the second iteration and
** current term is from the first iteration. So skip this term. */
assert( j==1 );
continue;
}
if( (chngToIN & sqlite3WhereGetMask(&pWInfo->sMaskSet,
pOrTerm->leftCursor))==0 ){
/* This term must be of the form t1.a==t2.b where t2 is in the
** chngToIN set but t1 is not. This term will be either preceded
** or follwed by an inverted copy (t2.b==t1.a). Skip this term
** and use its inversion. */
testcase( pOrTerm->wtFlags & TERM_COPIED );
testcase( pOrTerm->wtFlags & TERM_VIRTUAL );
assert( pOrTerm->wtFlags & (TERM_COPIED|TERM_VIRTUAL) );
continue;
}
iColumn = pOrTerm->u.leftColumn;
iCursor = pOrTerm->leftCursor;
pLeft = pOrTerm->pExpr->pLeft;
break;
}
if( i<0 ){
/* No candidate table+column was found. This can only occur
** on the second iteration */
assert( j==1 );
assert( IsPowerOfTwo(chngToIN) );
assert( chngToIN==sqlite3WhereGetMask(&pWInfo->sMaskSet, iCursor) );
break;
}
testcase( j==1 );
/* We have found a candidate table and column. Check to see if that
** table and column is common to every term in the OR clause */
okToChngToIN = 1;
for(; i>=0 && okToChngToIN; i--, pOrTerm++){
assert( pOrTerm->eOperator & WO_EQ );
if( pOrTerm->leftCursor!=iCursor ){
pOrTerm->wtFlags &= ~TERM_OR_OK;
}else if( pOrTerm->u.leftColumn!=iColumn || (iColumn==XN_EXPR
&& sqlite3ExprCompare(pParse, pOrTerm->pExpr->pLeft, pLeft, -1)
)){
okToChngToIN = 0;
}else{
int affLeft, affRight;
/* If the right-hand side is also a column, then the affinities
** of both right and left sides must be such that no type
** conversions are required on the right. (Ticket #2249)
*/
affRight = sqlite3ExprAffinity(pOrTerm->pExpr->pRight);
affLeft = sqlite3ExprAffinity(pOrTerm->pExpr->pLeft);
if( affRight!=0 && affRight!=affLeft ){
okToChngToIN = 0;
}else{
pOrTerm->wtFlags |= TERM_OR_OK;
}
}
}
}
/* At this point, okToChngToIN is true if original pTerm satisfies
** case 1. In that case, construct a new virtual term that is
** pTerm converted into an IN operator.
*/
if( okToChngToIN ){
Expr *pDup; /* A transient duplicate expression */
ExprList *pList = 0; /* The RHS of the IN operator */
Expr *pLeft = 0; /* The LHS of the IN operator */
Expr *pNew; /* The complete IN operator */
for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0; i--, pOrTerm++){
if( (pOrTerm->wtFlags & TERM_OR_OK)==0 ) continue;
assert( pOrTerm->eOperator & WO_EQ );
assert( pOrTerm->leftCursor==iCursor );
assert( pOrTerm->u.leftColumn==iColumn );
pDup = sqlite3ExprDup(db, pOrTerm->pExpr->pRight, 0);
pList = sqlite3ExprListAppend(pWInfo->pParse, pList, pDup);
pLeft = pOrTerm->pExpr->pLeft;
}
assert( pLeft!=0 );
pDup = sqlite3ExprDup(db, pLeft, 0);
pNew = sqlite3PExpr(pParse, TK_IN, pDup, 0);
if( pNew ){
int idxNew;
transferJoinMarkings(pNew, pExpr);
assert( !ExprHasProperty(pNew, EP_xIsSelect) );
pNew->x.pList = pList;
idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC);
testcase( idxNew==0 );
exprAnalyze(pSrc, pWC, idxNew);
/* pTerm = &pWC->a[idxTerm]; // would be needed if pTerm where used again */
markTermAsChild(pWC, idxNew, idxTerm);
}else{
sqlite3ExprListDelete(db, pList);
}
}
}
}
#endif /* !SQLITE_OMIT_OR_OPTIMIZATION && !SQLITE_OMIT_SUBQUERY */
/*
** We already know that pExpr is a binary operator where both operands are
** column references. This routine checks to see if pExpr is an equivalence
** relation:
** 1. The SQLITE_Transitive optimization must be enabled
** 2. Must be either an == or an IS operator
** 3. Not originating in the ON clause of an OUTER JOIN
** 4. The affinities of A and B must be compatible
** 5a. Both operands use the same collating sequence OR
** 5b. The overall collating sequence is BINARY
** If this routine returns TRUE, that means that the RHS can be substituted
** for the LHS anyplace else in the WHERE clause where the LHS column occurs.
** This is an optimization. No harm comes from returning 0. But if 1 is
** returned when it should not be, then incorrect answers might result.
*/
static int termIsEquivalence(Parse *pParse, Expr *pExpr){
char aff1, aff2;
CollSeq *pColl;
if( !OptimizationEnabled(pParse->db, SQLITE_Transitive) ) return 0;
if( pExpr->op!=TK_EQ && pExpr->op!=TK_IS ) return 0;
if( ExprHasProperty(pExpr, EP_FromJoin) ) return 0;
aff1 = sqlite3ExprAffinity(pExpr->pLeft);
aff2 = sqlite3ExprAffinity(pExpr->pRight);
if( aff1!=aff2
&& (!sqlite3IsNumericAffinity(aff1) || !sqlite3IsNumericAffinity(aff2))
){
return 0;
}
pColl = sqlite3BinaryCompareCollSeq(pParse, pExpr->pLeft, pExpr->pRight);
if( sqlite3IsBinary(pColl) ) return 1;
return sqlite3ExprCollSeqMatch(pParse, pExpr->pLeft, pExpr->pRight);
}
/*
** Recursively walk the expressions of a SELECT statement and generate
** a bitmask indicating which tables are used in that expression
** tree.
*/
static Bitmask exprSelectUsage(WhereMaskSet *pMaskSet, Select *pS){
Bitmask mask = 0;
while( pS ){
SrcList *pSrc = pS->pSrc;
mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pEList);
mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pGroupBy);
mask |= sqlite3WhereExprListUsage(pMaskSet, pS->pOrderBy);
mask |= sqlite3WhereExprUsage(pMaskSet, pS->pWhere);
mask |= sqlite3WhereExprUsage(pMaskSet, pS->pHaving);
if( ALWAYS(pSrc!=0) ){
int i;
for(i=0; i<pSrc->nSrc; i++){
mask |= exprSelectUsage(pMaskSet, pSrc->a[i].pSelect);
mask |= sqlite3WhereExprUsage(pMaskSet, pSrc->a[i].pOn);
if( pSrc->a[i].fg.isTabFunc ){
mask |= sqlite3WhereExprListUsage(pMaskSet, pSrc->a[i].u1.pFuncArg);
}
}
}
pS = pS->pPrior;
}
return mask;
}
/*
** Expression pExpr is one operand of a comparison operator that might
** be useful for indexing. This routine checks to see if pExpr appears
** in any index. Return TRUE (1) if pExpr is an indexed term and return
** FALSE (0) if not. If TRUE is returned, also set aiCurCol[0] to the cursor
** number of the table that is indexed and aiCurCol[1] to the column number
** of the column that is indexed, or XN_EXPR (-2) if an expression is being
** indexed.
**
** If pExpr is a TK_COLUMN column reference, then this routine always returns
** true even if that particular column is not indexed, because the column
** might be added to an automatic index later.
*/
static SQLITE_NOINLINE int exprMightBeIndexed2(
SrcList *pFrom, /* The FROM clause */
Bitmask mPrereq, /* Bitmask of FROM clause terms referenced by pExpr */
int *aiCurCol, /* Write the referenced table cursor and column here */
Expr *pExpr /* An operand of a comparison operator */
){
Index *pIdx;
int i;
int iCur;
for(i=0; mPrereq>1; i++, mPrereq>>=1){}
iCur = pFrom->a[i].iCursor;
for(pIdx=pFrom->a[i].pTab->pIndex; pIdx; pIdx=pIdx->pNext){
if( pIdx->aColExpr==0 ) continue;
for(i=0; i<pIdx->nKeyCol; i++){
if( pIdx->aiColumn[i]!=XN_EXPR ) continue;
if( sqlite3ExprCompareSkip(pExpr, pIdx->aColExpr->a[i].pExpr, iCur)==0 ){
aiCurCol[0] = iCur;
aiCurCol[1] = XN_EXPR;
return 1;
}
}
}
return 0;
}
static int exprMightBeIndexed(
SrcList *pFrom, /* The FROM clause */
Bitmask mPrereq, /* Bitmask of FROM clause terms referenced by pExpr */
int *aiCurCol, /* Write the referenced table cursor & column here */
Expr *pExpr, /* An operand of a comparison operator */
int op /* The specific comparison operator */
){
/* If this expression is a vector to the left or right of a
** inequality constraint (>, <, >= or <=), perform the processing
** on the first element of the vector. */
assert( TK_GT+1==TK_LE && TK_GT+2==TK_LT && TK_GT+3==TK_GE );
assert( TK_IS<TK_GE && TK_ISNULL<TK_GE && TK_IN<TK_GE );
assert( op<=TK_GE );
if( pExpr->op==TK_VECTOR && (op>=TK_GT && ALWAYS(op<=TK_GE)) ){
pExpr = pExpr->x.pList->a[0].pExpr;
}
if( pExpr->op==TK_COLUMN ){
aiCurCol[0] = pExpr->iTable;
aiCurCol[1] = pExpr->iColumn;
return 1;
}
if( mPrereq==0 ) return 0; /* No table references */
if( (mPrereq&(mPrereq-1))!=0 ) return 0; /* Refs more than one table */
return exprMightBeIndexed2(pFrom,mPrereq,aiCurCol,pExpr);
}
/*
** The input to this routine is an WhereTerm structure with only the
** "pExpr" field filled in. The job of this routine is to analyze the
** subexpression and populate all the other fields of the WhereTerm
** structure.
**
** If the expression is of the form "<expr> <op> X" it gets commuted
** to the standard form of "X <op> <expr>".
**
** If the expression is of the form "X <op> Y" where both X and Y are
** columns, then the original expression is unchanged and a new virtual
** term of the form "Y <op> X" is added to the WHERE clause and
** analyzed separately. The original term is marked with TERM_COPIED
** and the new term is marked with TERM_DYNAMIC (because it's pExpr
** needs to be freed with the WhereClause) and TERM_VIRTUAL (because it
** is a commuted copy of a prior term.) The original term has nChild=1
** and the copy has idxParent set to the index of the original term.
*/
static void exprAnalyze(
SrcList *pSrc, /* the FROM clause */
WhereClause *pWC, /* the WHERE clause */
int idxTerm /* Index of the term to be analyzed */
){
WhereInfo *pWInfo = pWC->pWInfo; /* WHERE clause processing context */
WhereTerm *pTerm; /* The term to be analyzed */
WhereMaskSet *pMaskSet; /* Set of table index masks */
Expr *pExpr; /* The expression to be analyzed */
Bitmask prereqLeft; /* Prerequesites of the pExpr->pLeft */
Bitmask prereqAll; /* Prerequesites of pExpr */
Bitmask extraRight = 0; /* Extra dependencies on LEFT JOIN */
Expr *pStr1 = 0; /* RHS of LIKE/GLOB operator */
int isComplete = 0; /* RHS of LIKE/GLOB ends with wildcard */
int noCase = 0; /* uppercase equivalent to lowercase */
int op; /* Top-level operator. pExpr->op */
Parse *pParse = pWInfo->pParse; /* Parsing context */
sqlite3 *db = pParse->db; /* Database connection */
unsigned char eOp2 = 0; /* op2 value for LIKE/REGEXP/GLOB */
int nLeft; /* Number of elements on left side vector */
if( db->mallocFailed ){
return;
}
pTerm = &pWC->a[idxTerm];
pMaskSet = &pWInfo->sMaskSet;
pExpr = pTerm->pExpr;
assert( pExpr->op!=TK_AS && pExpr->op!=TK_COLLATE );
prereqLeft = sqlite3WhereExprUsage(pMaskSet, pExpr->pLeft);
op = pExpr->op;
if( op==TK_IN ){
assert( pExpr->pRight==0 );
if( sqlite3ExprCheckIN(pParse, pExpr) ) return;
if( ExprHasProperty(pExpr, EP_xIsSelect) ){
pTerm->prereqRight = exprSelectUsage(pMaskSet, pExpr->x.pSelect);
}else{
pTerm->prereqRight = sqlite3WhereExprListUsage(pMaskSet, pExpr->x.pList);
}
}else if( op==TK_ISNULL ){
pTerm->prereqRight = 0;
}else{
pTerm->prereqRight = sqlite3WhereExprUsage(pMaskSet, pExpr->pRight);
}
pMaskSet->bVarSelect = 0;
prereqAll = sqlite3WhereExprUsageNN(pMaskSet, pExpr);
if( pMaskSet->bVarSelect ) pTerm->wtFlags |= TERM_VARSELECT;
if( ExprHasProperty(pExpr, EP_FromJoin) ){
Bitmask x = sqlite3WhereGetMask(pMaskSet, pExpr->iRightJoinTable);
prereqAll |= x;
extraRight = x-1; /* ON clause terms may not be used with an index
** on left table of a LEFT JOIN. Ticket #3015 */
if( (prereqAll>>1)>=x ){
sqlite3ErrorMsg(pParse, "ON clause references tables to its right");
return;
}
}
pTerm->prereqAll = prereqAll;
pTerm->leftCursor = -1;
pTerm->iParent = -1;
pTerm->eOperator = 0;
if( allowedOp(op) ){
int aiCurCol[2];
Expr *pLeft = sqlite3ExprSkipCollate(pExpr->pLeft);
Expr *pRight = sqlite3ExprSkipCollate(pExpr->pRight);
u16 opMask = (pTerm->prereqRight & prereqLeft)==0 ? WO_ALL : WO_EQUIV;
if( pTerm->iField>0 ){
assert( op==TK_IN );
assert( pLeft->op==TK_VECTOR );
pLeft = pLeft->x.pList->a[pTerm->iField-1].pExpr;
}
if( exprMightBeIndexed(pSrc, prereqLeft, aiCurCol, pLeft, op) ){
pTerm->leftCursor = aiCurCol[0];
pTerm->u.leftColumn = aiCurCol[1];
pTerm->eOperator = operatorMask(op) & opMask;
}
if( op==TK_IS ) pTerm->wtFlags |= TERM_IS;
if( pRight
&& exprMightBeIndexed(pSrc, pTerm->prereqRight, aiCurCol, pRight, op)
){
WhereTerm *pNew;
Expr *pDup;
u16 eExtraOp = 0; /* Extra bits for pNew->eOperator */
assert( pTerm->iField==0 );
if( pTerm->leftCursor>=0 ){
int idxNew;
pDup = sqlite3ExprDup(db, pExpr, 0);
if( db->mallocFailed ){
sqlite3ExprDelete(db, pDup);
return;
}
idxNew = whereClauseInsert(pWC, pDup, TERM_VIRTUAL|TERM_DYNAMIC);
if( idxNew==0 ) return;
pNew = &pWC->a[idxNew];
markTermAsChild(pWC, idxNew, idxTerm);
if( op==TK_IS ) pNew->wtFlags |= TERM_IS;
pTerm = &pWC->a[idxTerm];
pTerm->wtFlags |= TERM_COPIED;
if( termIsEquivalence(pParse, pDup) ){
pTerm->eOperator |= WO_EQUIV;
eExtraOp = WO_EQUIV;
}
}else{
pDup = pExpr;
pNew = pTerm;
}
pNew->wtFlags |= exprCommute(pParse, pDup);
pNew->leftCursor = aiCurCol[0];
pNew->u.leftColumn = aiCurCol[1];
testcase( (prereqLeft | extraRight) != prereqLeft );
pNew->prereqRight = prereqLeft | extraRight;
pNew->prereqAll = prereqAll;
pNew->eOperator = (operatorMask(pDup->op) + eExtraOp) & opMask;
}
}
#ifndef SQLITE_OMIT_BETWEEN_OPTIMIZATION
/* If a term is the BETWEEN operator, create two new virtual terms
** that define the range that the BETWEEN implements. For example:
**
** a BETWEEN b AND c
**
** is converted into:
**
** (a BETWEEN b AND c) AND (a>=b) AND (a<=c)
**
** The two new terms are added onto the end of the WhereClause object.
** The new terms are "dynamic" and are children of the original BETWEEN
** term. That means that if the BETWEEN term is coded, the children are
** skipped. Or, if the children are satisfied by an index, the original
** BETWEEN term is skipped.
*/
else if( pExpr->op==TK_BETWEEN && pWC->op==TK_AND ){
ExprList *pList = pExpr->x.pList;
int i;
static const u8 ops[] = {TK_GE, TK_LE};
assert( pList!=0 );
assert( pList->nExpr==2 );
for(i=0; i<2; i++){
Expr *pNewExpr;
int idxNew;
pNewExpr = sqlite3PExpr(pParse, ops[i],
sqlite3ExprDup(db, pExpr->pLeft, 0),
sqlite3ExprDup(db, pList->a[i].pExpr, 0));
transferJoinMarkings(pNewExpr, pExpr);
idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
testcase( idxNew==0 );
exprAnalyze(pSrc, pWC, idxNew);
pTerm = &pWC->a[idxTerm];
markTermAsChild(pWC, idxNew, idxTerm);
}
}
#endif /* SQLITE_OMIT_BETWEEN_OPTIMIZATION */
#if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
/* Analyze a term that is composed of two or more subterms connected by
** an OR operator.
*/
else if( pExpr->op==TK_OR ){
assert( pWC->op==TK_AND );
exprAnalyzeOrTerm(pSrc, pWC, idxTerm);
pTerm = &pWC->a[idxTerm];
}
#endif /* SQLITE_OMIT_OR_OPTIMIZATION */
#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
/* Add constraints to reduce the search space on a LIKE or GLOB
** operator.
**
** A like pattern of the form "x LIKE 'aBc%'" is changed into constraints
**
** x>='ABC' AND x<'abd' AND x LIKE 'aBc%'
**
** The last character of the prefix "abc" is incremented to form the
** termination condition "abd". If case is not significant (the default
** for LIKE) then the lower-bound is made all uppercase and the upper-
** bound is made all lowercase so that the bounds also work when comparing
** BLOBs.
*/
if( pWC->op==TK_AND
&& isLikeOrGlob(pParse, pExpr, &pStr1, &isComplete, &noCase)
){
Expr *pLeft; /* LHS of LIKE/GLOB operator */
Expr *pStr2; /* Copy of pStr1 - RHS of LIKE/GLOB operator */
Expr *pNewExpr1;
Expr *pNewExpr2;
int idxNew1;
int idxNew2;
const char *zCollSeqName; /* Name of collating sequence */
const u16 wtFlags = TERM_LIKEOPT | TERM_VIRTUAL | TERM_DYNAMIC;
pLeft = pExpr->x.pList->a[1].pExpr;
pStr2 = sqlite3ExprDup(db, pStr1, 0);
/* Convert the lower bound to upper-case and the upper bound to
** lower-case (upper-case is less than lower-case in ASCII) so that
** the range constraints also work for BLOBs
*/
if( noCase && !pParse->db->mallocFailed ){
int i;
char c;
pTerm->wtFlags |= TERM_LIKE;
for(i=0; (c = pStr1->u.zToken[i])!=0; i++){
pStr1->u.zToken[i] = sqlite3Toupper(c);
pStr2->u.zToken[i] = sqlite3Tolower(c);
}
}
if( !db->mallocFailed ){
u8 c, *pC; /* Last character before the first wildcard */
pC = (u8*)&pStr2->u.zToken[sqlite3Strlen30(pStr2->u.zToken)-1];
c = *pC;
if( noCase ){
/* The point is to increment the last character before the first
** wildcard. But if we increment '@', that will push it into the
** alphabetic range where case conversions will mess up the
** inequality. To avoid this, make sure to also run the full
** LIKE on all candidate expressions by clearing the isComplete flag
*/
if( c=='A'-1 ) isComplete = 0;
c = sqlite3UpperToLower[c];
}
*pC = c + 1;
}
zCollSeqName = noCase ? "NOCASE" : sqlite3StrBINARY;
pNewExpr1 = sqlite3ExprDup(db, pLeft, 0);
pNewExpr1 = sqlite3PExpr(pParse, TK_GE,
sqlite3ExprAddCollateString(pParse,pNewExpr1,zCollSeqName),
pStr1);
transferJoinMarkings(pNewExpr1, pExpr);
idxNew1 = whereClauseInsert(pWC, pNewExpr1, wtFlags);
testcase( idxNew1==0 );
exprAnalyze(pSrc, pWC, idxNew1);
pNewExpr2 = sqlite3ExprDup(db, pLeft, 0);
pNewExpr2 = sqlite3PExpr(pParse, TK_LT,
sqlite3ExprAddCollateString(pParse,pNewExpr2,zCollSeqName),
pStr2);
transferJoinMarkings(pNewExpr2, pExpr);
idxNew2 = whereClauseInsert(pWC, pNewExpr2, wtFlags);
testcase( idxNew2==0 );
exprAnalyze(pSrc, pWC, idxNew2);
pTerm = &pWC->a[idxTerm];
if( isComplete ){
markTermAsChild(pWC, idxNew1, idxTerm);
markTermAsChild(pWC, idxNew2, idxTerm);
}
}
#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
#ifndef SQLITE_OMIT_VIRTUALTABLE
/* Add a WO_AUX auxiliary term to the constraint set if the
** current expression is of the form "column OP expr" where OP
** is an operator that gets passed into virtual tables but which is
** not normally optimized for ordinary tables. In other words, OP
** is one of MATCH, LIKE, GLOB, REGEXP, !=, IS, IS NOT, or NOT NULL.
** This information is used by the xBestIndex methods of
** virtual tables. The native query optimizer does not attempt
** to do anything with MATCH functions.
*/
if( pWC->op==TK_AND ){
Expr *pRight = 0, *pLeft = 0;
int res = isAuxiliaryVtabOperator(db, pExpr, &eOp2, &pLeft, &pRight);
while( res-- > 0 ){
int idxNew;
WhereTerm *pNewTerm;
Bitmask prereqColumn, prereqExpr;
prereqExpr = sqlite3WhereExprUsage(pMaskSet, pRight);
prereqColumn = sqlite3WhereExprUsage(pMaskSet, pLeft);
if( (prereqExpr & prereqColumn)==0 ){
Expr *pNewExpr;
pNewExpr = sqlite3PExpr(pParse, TK_MATCH,
0, sqlite3ExprDup(db, pRight, 0));
if( ExprHasProperty(pExpr, EP_FromJoin) && pNewExpr ){
ExprSetProperty(pNewExpr, EP_FromJoin);
}
idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
testcase( idxNew==0 );
pNewTerm = &pWC->a[idxNew];
pNewTerm->prereqRight = prereqExpr;
pNewTerm->leftCursor = pLeft->iTable;
pNewTerm->u.leftColumn = pLeft->iColumn;
pNewTerm->eOperator = WO_AUX;
pNewTerm->eMatchOp = eOp2;
markTermAsChild(pWC, idxNew, idxTerm);
pTerm = &pWC->a[idxTerm];
pTerm->wtFlags |= TERM_COPIED;
pNewTerm->prereqAll = pTerm->prereqAll;
}
SWAP(Expr*, pLeft, pRight);
}
}
#endif /* SQLITE_OMIT_VIRTUALTABLE */
/* If there is a vector == or IS term - e.g. "(a, b) == (?, ?)" - create
** new terms for each component comparison - "a = ?" and "b = ?". The
** new terms completely replace the original vector comparison, which is
** no longer used.
**
** This is only required if at least one side of the comparison operation
** is not a sub-select. */
if( pWC->op==TK_AND
&& (pExpr->op==TK_EQ || pExpr->op==TK_IS)
&& (nLeft = sqlite3ExprVectorSize(pExpr->pLeft))>1
&& sqlite3ExprVectorSize(pExpr->pRight)==nLeft
&& ( (pExpr->pLeft->flags & EP_xIsSelect)==0
|| (pExpr->pRight->flags & EP_xIsSelect)==0)
){
int i;
for(i=0; i<nLeft; i++){
int idxNew;
Expr *pNew;
Expr *pLeft = sqlite3ExprForVectorField(pParse, pExpr->pLeft, i);
Expr *pRight = sqlite3ExprForVectorField(pParse, pExpr->pRight, i);
pNew = sqlite3PExpr(pParse, pExpr->op, pLeft, pRight);
transferJoinMarkings(pNew, pExpr);
idxNew = whereClauseInsert(pWC, pNew, TERM_DYNAMIC);
exprAnalyze(pSrc, pWC, idxNew);
}
pTerm = &pWC->a[idxTerm];
pTerm->wtFlags |= TERM_CODED|TERM_VIRTUAL; /* Disable the original */
pTerm->eOperator = 0;
}
/* If there is a vector IN term - e.g. "(a, b) IN (SELECT ...)" - create
** a virtual term for each vector component. The expression object
** used by each such virtual term is pExpr (the full vector IN(...)
** expression). The WhereTerm.iField variable identifies the index within
** the vector on the LHS that the virtual term represents.
**
** This only works if the RHS is a simple SELECT, not a compound
*/
if( pWC->op==TK_AND && pExpr->op==TK_IN && pTerm->iField==0
&& pExpr->pLeft->op==TK_VECTOR
&& pExpr->x.pSelect->pPrior==0
){
int i;
for(i=0; i<sqlite3ExprVectorSize(pExpr->pLeft); i++){
int idxNew;
idxNew = whereClauseInsert(pWC, pExpr, TERM_VIRTUAL);
pWC->a[idxNew].iField = i+1;
exprAnalyze(pSrc, pWC, idxNew);
markTermAsChild(pWC, idxNew, idxTerm);
}
}
#ifdef SQLITE_ENABLE_STAT4
/* When sqlite_stat4 histogram data is available an operator of the
** form "x IS NOT NULL" can sometimes be evaluated more efficiently
** as "x>NULL" if x is not an INTEGER PRIMARY KEY. So construct a
** virtual term of that form.
**
** Note that the virtual term must be tagged with TERM_VNULL.
*/
if( pExpr->op==TK_NOTNULL
&& pExpr->pLeft->op==TK_COLUMN
&& pExpr->pLeft->iColumn>=0
&& !ExprHasProperty(pExpr, EP_FromJoin)
&& OptimizationEnabled(db, SQLITE_Stat4)
){
Expr *pNewExpr;
Expr *pLeft = pExpr->pLeft;
int idxNew;
WhereTerm *pNewTerm;
pNewExpr = sqlite3PExpr(pParse, TK_GT,
sqlite3ExprDup(db, pLeft, 0),
sqlite3ExprAlloc(db, TK_NULL, 0, 0));
idxNew = whereClauseInsert(pWC, pNewExpr,
TERM_VIRTUAL|TERM_DYNAMIC|TERM_VNULL);
if( idxNew ){
pNewTerm = &pWC->a[idxNew];
pNewTerm->prereqRight = 0;
pNewTerm->leftCursor = pLeft->iTable;
pNewTerm->u.leftColumn = pLeft->iColumn;
pNewTerm->eOperator = WO_GT;
markTermAsChild(pWC, idxNew, idxTerm);
pTerm = &pWC->a[idxTerm];
pTerm->wtFlags |= TERM_COPIED;
pNewTerm->prereqAll = pTerm->prereqAll;
}
}
#endif /* SQLITE_ENABLE_STAT4 */
/* Prevent ON clause terms of a LEFT JOIN from being used to drive
** an index for tables to the left of the join.
*/
testcase( pTerm!=&pWC->a[idxTerm] );
pTerm = &pWC->a[idxTerm];
pTerm->prereqRight |= extraRight;
}
/***************************************************************************
** Routines with file scope above. Interface to the rest of the where.c
** subsystem follows.
***************************************************************************/
/*
** This routine identifies subexpressions in the WHERE clause where
** each subexpression is separated by the AND operator or some other
** operator specified in the op parameter. The WhereClause structure
** is filled with pointers to subexpressions. For example:
**
** WHERE a=='hello' AND coalesce(b,11)<10 AND (c+12!=d OR c==22)
** \________/ \_______________/ \________________/
** slot[0] slot[1] slot[2]
**
** The original WHERE clause in pExpr is unaltered. All this routine
** does is make slot[] entries point to substructure within pExpr.
**
** In the previous sentence and in the diagram, "slot[]" refers to
** the WhereClause.a[] array. The slot[] array grows as needed to contain
** all terms of the WHERE clause.
*/
void sqlite3WhereSplit(WhereClause *pWC, Expr *pExpr, u8 op){
Expr *pE2 = sqlite3ExprSkipCollateAndLikely(pExpr);
pWC->op = op;
if( pE2==0 ) return;
if( pE2->op!=op ){
whereClauseInsert(pWC, pExpr, 0);
}else{
sqlite3WhereSplit(pWC, pE2->pLeft, op);
sqlite3WhereSplit(pWC, pE2->pRight, op);
}
}
/*
** Initialize a preallocated WhereClause structure.
*/
void sqlite3WhereClauseInit(
WhereClause *pWC, /* The WhereClause to be initialized */
WhereInfo *pWInfo /* The WHERE processing context */
){
pWC->pWInfo = pWInfo;
pWC->hasOr = 0;
pWC->pOuter = 0;
pWC->nTerm = 0;
pWC->nSlot = ArraySize(pWC->aStatic);
pWC->a = pWC->aStatic;
}
/*
** Deallocate a WhereClause structure. The WhereClause structure
** itself is not freed. This routine is the inverse of
** sqlite3WhereClauseInit().
*/
void sqlite3WhereClauseClear(WhereClause *pWC){
int i;
WhereTerm *a;
sqlite3 *db = pWC->pWInfo->pParse->db;
for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){
if( a->wtFlags & TERM_DYNAMIC ){
sqlite3ExprDelete(db, a->pExpr);
}
if( a->wtFlags & TERM_ORINFO ){
whereOrInfoDelete(db, a->u.pOrInfo);
}else if( a->wtFlags & TERM_ANDINFO ){
whereAndInfoDelete(db, a->u.pAndInfo);
}
}
if( pWC->a!=pWC->aStatic ){
sqlite3DbFree(db, pWC->a);
}
}
/*
** These routines walk (recursively) an expression tree and generate
** a bitmask indicating which tables are used in that expression
** tree.
*/
Bitmask sqlite3WhereExprUsageNN(WhereMaskSet *pMaskSet, Expr *p){
Bitmask mask;
if( p->op==TK_COLUMN && !ExprHasProperty(p, EP_FixedCol) ){
return sqlite3WhereGetMask(pMaskSet, p->iTable);
}else if( ExprHasProperty(p, EP_TokenOnly|EP_Leaf) ){
assert( p->op!=TK_IF_NULL_ROW );
return 0;
}
mask = (p->op==TK_IF_NULL_ROW) ? sqlite3WhereGetMask(pMaskSet, p->iTable) : 0;
if( p->pLeft ) mask |= sqlite3WhereExprUsageNN(pMaskSet, p->pLeft);
if( p->pRight ){
mask |= sqlite3WhereExprUsageNN(pMaskSet, p->pRight);
assert( p->x.pList==0 );
}else if( ExprHasProperty(p, EP_xIsSelect) ){
if( ExprHasProperty(p, EP_VarSelect) ) pMaskSet->bVarSelect = 1;
mask |= exprSelectUsage(pMaskSet, p->x.pSelect);
}else if( p->x.pList ){
mask |= sqlite3WhereExprListUsage(pMaskSet, p->x.pList);
}
#ifndef SQLITE_OMIT_WINDOWFUNC
if( p->op==TK_FUNCTION && p->y.pWin ){
mask |= sqlite3WhereExprListUsage(pMaskSet, p->y.pWin->pPartition);
mask |= sqlite3WhereExprListUsage(pMaskSet, p->y.pWin->pOrderBy);
}
#endif
return mask;
}
Bitmask sqlite3WhereExprUsage(WhereMaskSet *pMaskSet, Expr *p){
return p ? sqlite3WhereExprUsageNN(pMaskSet,p) : 0;
}
Bitmask sqlite3WhereExprListUsage(WhereMaskSet *pMaskSet, ExprList *pList){
int i;
Bitmask mask = 0;
if( pList ){
for(i=0; i<pList->nExpr; i++){
mask |= sqlite3WhereExprUsage(pMaskSet, pList->a[i].pExpr);
}
}
return mask;
}
/*
** Call exprAnalyze on all terms in a WHERE clause.
**
** Note that exprAnalyze() might add new virtual terms onto the
** end of the WHERE clause. We do not want to analyze these new
** virtual terms, so start analyzing at the end and work forward
** so that the added virtual terms are never processed.
*/
void sqlite3WhereExprAnalyze(
SrcList *pTabList, /* the FROM clause */
WhereClause *pWC /* the WHERE clause to be analyzed */
){
int i;
for(i=pWC->nTerm-1; i>=0; i--){
exprAnalyze(pTabList, pWC, i);
}
}
/*
** For table-valued-functions, transform the function arguments into
** new WHERE clause terms.
**
** Each function argument translates into an equality constraint against
** a HIDDEN column in the table.
*/
void sqlite3WhereTabFuncArgs(
Parse *pParse, /* Parsing context */
struct SrcList_item *pItem, /* The FROM clause term to process */
WhereClause *pWC /* Xfer function arguments to here */
){
Table *pTab;
int j, k;
ExprList *pArgs;
Expr *pColRef;
Expr *pTerm;
if( pItem->fg.isTabFunc==0 ) return;
pTab = pItem->pTab;
assert( pTab!=0 );
pArgs = pItem->u1.pFuncArg;
if( pArgs==0 ) return;
for(j=k=0; j<pArgs->nExpr; j++){
Expr *pRhs;
while( k<pTab->nCol && (pTab->aCol[k].colFlags & COLFLAG_HIDDEN)==0 ){k++;}
if( k>=pTab->nCol ){
sqlite3ErrorMsg(pParse, "too many arguments on %s() - max %d",
pTab->zName, j);
return;
}
pColRef = sqlite3ExprAlloc(pParse->db, TK_COLUMN, 0, 0);
if( pColRef==0 ) return;
pColRef->iTable = pItem->iCursor;
pColRef->iColumn = k++;
pColRef->y.pTab = pTab;
pRhs = sqlite3PExpr(pParse, TK_UPLUS,
sqlite3ExprDup(pParse->db, pArgs->a[j].pExpr, 0), 0);
pTerm = sqlite3PExpr(pParse, TK_EQ, pColRef, pRhs);
whereClauseInsert(pWC, pTerm, TERM_DYNAMIC);
}
}