/*
** Walk an expression tree. Return 1 if the expression is constant
** and 0 if it involves variables.
**
** For the purposes of this function, a double-quoted string (ex: "abc")
** is considered a variable but a single-quoted string (ex: 'abc') is
** a constant.
*/
int sqliteExprIsConstant(Expr *p){
switch( p->op ){
case TK_ID:
case TK_COLUMN:
case TK_DOT:
case TK_FUNCTION:
return 0;
case TK_NULL:
case TK_STRING:
case TK_INTEGER:
case TK_FLOAT:
case TK_VARIABLE:
return 1;
default: {
if( p->pLeft && !sqliteExprIsConstant(p->pLeft) ) return 0;
if( p->pRight && !sqliteExprIsConstant(p->pRight) ) return 0;
if( p->pList ){
int i;
for(i=0; i<p->pList->nExpr; i++){
if( !sqliteExprIsConstant(p->pList->a[i].pExpr) ) return 0;
}
}
return p->pLeft!=0 || p->pRight!=0 || (p->pList && p->pList->nExpr>0);
}
}
return 0;
}
/*
** Generate the beginning of the loop used for WHERE clause processing.
** The return value is a pointer to an (opaque) structure that contains
** information needed to terminate the loop. Later, the calling routine
** should invoke sqliteWhereEnd() with the return value of this function
** in order to complete the WHERE clause processing.
**
** If an error occurs, this routine returns NULL.
**
** The basic idea is to do a nested loop, one loop for each table in
** the FROM clause of a select. (INSERT and UPDATE statements are the
** same as a SELECT with only a single table in the FROM clause.) For
** example, if the SQL is this:
**
** SELECT * FROM t1, t2, t3 WHERE ...;
**
** Then the code generated is conceptually like the following:
**
** foreach row1 in t1 do \ Code generated
** foreach row2 in t2 do |-- by sqliteWhereBegin()
** foreach row3 in t3 do /
** ...
** end \ Code generated
** end |-- by sqliteWhereEnd()
** end /
**
** There are Btree cursors associated with each table. t1 uses cursor
** number pTabList->a[0].iCursor. t2 uses the cursor pTabList->a[1].iCursor.
** And so forth. This routine generates code to open those VDBE cursors
** and sqliteWhereEnd() generates the code to close them.
**
** If the WHERE clause is empty, the foreach loops must each scan their
** entire tables. Thus a three-way join is an O(N^3) operation. But if
** the tables have indices and there are terms in the WHERE clause that
** refer to those indices, a complete table scan can be avoided and the
** code will run much faster. Most of the work of this routine is checking
** to see if there are indices that can be used to speed up the loop.
**
** Terms of the WHERE clause are also used to limit which rows actually
** make it to the "..." in the middle of the loop. After each "foreach",
** terms of the WHERE clause that use only terms in that loop and outer
** loops are evaluated and if false a jump is made around all subsequent
** inner loops (or around the "..." if the test occurs within the inner-
** most loop)
**
** OUTER JOINS
**
** An outer join of tables t1 and t2 is conceptally coded as follows:
**
** foreach row1 in t1 do
** flag = 0
** foreach row2 in t2 do
** start:
** ...
** flag = 1
** end
** if flag==0 then
** move the row2 cursor to a null row
** goto start
** fi
** end
**
** ORDER BY CLAUSE PROCESSING
**
** *ppOrderBy is a pointer to the ORDER BY clause of a SELECT statement,
** if there is one. If there is no ORDER BY clause or if this routine
** is called from an UPDATE or DELETE statement, then ppOrderBy is NULL.
**
** If an index can be used so that the natural output order of the table
** scan is correct for the ORDER BY clause, then that index is used and
** *ppOrderBy is set to NULL. This is an optimization that prevents an
** unnecessary sort of the result set if an index appropriate for the
** ORDER BY clause already exists.
**
** If the where clause loops cannot be arranged to provide the correct
** output order, then the *ppOrderBy is unchanged.
*/
WhereInfo *sqliteWhereBegin(
Parse *pParse, /* The parser context */
SrcList *pTabList, /* A list of all tables to be scanned */
Expr *pWhere, /* The WHERE clause */
int pushKey, /* If TRUE, leave the table key on the stack */
ExprList **ppOrderBy /* An ORDER BY clause, or NULL */
){
int i; /* Loop counter */
WhereInfo *pWInfo; /* Will become the return value of this function */
Vdbe *v = pParse->pVdbe; /* The virtual database engine */
int brk, cont = 0; /* Addresses used during code generation */
int nExpr; /* Number of subexpressions in the WHERE clause */
int loopMask; /* One bit set for each outer loop */
int haveKey; /* True if KEY is on the stack */
ExprMaskSet maskSet; /* The expression mask set */
int iDirectEq[32]; /* Term of the form ROWID==X for the N-th table */
int iDirectLt[32]; /* Term of the form ROWID<X or ROWID<=X */
int iDirectGt[32]; /* Term of the form ROWID>X or ROWID>=X */
ExprInfo aExpr[101]; /* The WHERE clause is divided into these expressions */
/* pushKey is only allowed if there is a single table (as in an INSERT or
** UPDATE statement)
*/
assert( pushKey==0 || pTabList->nSrc==1 );
/* Split the WHERE clause into separate subexpressions where each
** subexpression is separated by an AND operator. If the aExpr[]
** array fills up, the last entry might point to an expression which
** contains additional unfactored AND operators.
*/
initMaskSet(&maskSet);
memset(aExpr, 0, sizeof(aExpr));
nExpr = exprSplit(ARRAYSIZE(aExpr), aExpr, pWhere);
if( nExpr==ARRAYSIZE(aExpr) ){
sqliteErrorMsg(pParse, "WHERE clause too complex - no more "
"than %d terms allowed", (int)ARRAYSIZE(aExpr)-1);
return 0;
}
/* Allocate and initialize the WhereInfo structure that will become the
** return value.
*/
pWInfo = sqliteMalloc( sizeof(WhereInfo) + pTabList->nSrc*sizeof(WhereLevel));
if( sqlite_malloc_failed ){
sqliteFree(pWInfo);
return 0;
}
pWInfo->pParse = pParse;
pWInfo->pTabList = pTabList;
pWInfo->peakNTab = pWInfo->savedNTab = pParse->nTab;
pWInfo->iBreak = sqliteVdbeMakeLabel(v);
/* Special case: a WHERE clause that is constant. Evaluate the
** expression and either jump over all of the code or fall thru.
*/
if( pWhere && (pTabList->nSrc==0 || sqliteExprIsConstant(pWhere)) ){
sqliteExprIfFalse(pParse, pWhere, pWInfo->iBreak, 1);
pWhere = 0;
}
/* Analyze all of the subexpressions.
*/
for(i=0; i<nExpr; i++){
exprAnalyze(&maskSet, &aExpr[i]);
/* If we are executing a trigger body, remove all references to
** new.* and old.* tables from the prerequisite masks.
*/
if( pParse->trigStack ){
int x;
if( (x = pParse->trigStack->newIdx) >= 0 ){
int mask = ~getMask(&maskSet, x);
aExpr[i].prereqRight &= mask;
aExpr[i].prereqLeft &= mask;
aExpr[i].prereqAll &= mask;
}
if( (x = pParse->trigStack->oldIdx) >= 0 ){
int mask = ~getMask(&maskSet, x);
aExpr[i].prereqRight &= mask;
aExpr[i].prereqLeft &= mask;
aExpr[i].prereqAll &= mask;
}
}
}
/* Figure out what index to use (if any) for each nested loop.
** Make pWInfo->a[i].pIdx point to the index to use for the i-th nested
** loop where i==0 is the outer loop and i==pTabList->nSrc-1 is the inner
** loop.
**
** If terms exist that use the ROWID of any table, then set the
** iDirectEq[], iDirectLt[], or iDirectGt[] elements for that table
** to the index of the term containing the ROWID. We always prefer
** to use a ROWID which can directly access a table rather than an
** index which requires reading an index first to get the rowid then
** doing a second read of the actual database table.
**
** Actually, if there are more than 32 tables in the join, only the
** first 32 tables are candidates for indices. This is (again) due
** to the limit of 32 bits in an integer bitmask.
*/
loopMask = 0;
for(i=0; i<pTabList->nSrc && i<ARRAYSIZE(iDirectEq); i++){
int j;
int iCur = pTabList->a[i].iCursor; /* The cursor for this table */
int mask = getMask(&maskSet, iCur); /* Cursor mask for this table */
Table *pTab = pTabList->a[i].pTab;
Index *pIdx;
Index *pBestIdx = 0;
int bestScore = 0;
/* Check to see if there is an expression that uses only the
** ROWID field of this table. For terms of the form ROWID==expr
** set iDirectEq[i] to the index of the term. For terms of the
** form ROWID<expr or ROWID<=expr set iDirectLt[i] to the term index.
** For terms like ROWID>expr or ROWID>=expr set iDirectGt[i].
**
** (Added:) Treat ROWID IN expr like ROWID=expr.
*/
pWInfo->a[i].iCur = -1;
iDirectEq[i] = -1;
iDirectLt[i] = -1;
iDirectGt[i] = -1;
for(j=0; j<nExpr; j++){
if( aExpr[j].idxLeft==iCur && aExpr[j].p->pLeft->iColumn<0
&& (aExpr[j].prereqRight & loopMask)==aExpr[j].prereqRight ){
switch( aExpr[j].p->op ){
case TK_IN:
case TK_EQ: iDirectEq[i] = j; break;
case TK_LE:
case TK_LT: iDirectLt[i] = j; break;
case TK_GE:
case TK_GT: iDirectGt[i] = j; break;
}
}
if( aExpr[j].idxRight==iCur && aExpr[j].p->pRight->iColumn<0
&& (aExpr[j].prereqLeft & loopMask)==aExpr[j].prereqLeft ){
switch( aExpr[j].p->op ){
case TK_EQ: iDirectEq[i] = j; break;
case TK_LE:
case TK_LT: iDirectGt[i] = j; break;
case TK_GE:
case TK_GT: iDirectLt[i] = j; break;
}
}
}
if( iDirectEq[i]>=0 ){
loopMask |= mask;
pWInfo->a[i].pIdx = 0;
continue;
}
/* Do a search for usable indices. Leave pBestIdx pointing to
** the "best" index. pBestIdx is left set to NULL if no indices
** are usable.
**
** The best index is determined as follows. For each of the
** left-most terms that is fixed by an equality operator, add
** 8 to the score. The right-most term of the index may be
** constrained by an inequality. Add 1 if for an "x<..." constraint
** and add 2 for an "x>..." constraint. Chose the index that
** gives the best score.
**
** This scoring system is designed so that the score can later be
** used to determine how the index is used. If the score&7 is 0
** then all constraints are equalities. If score&1 is not 0 then
** there is an inequality used as a termination key. (ex: "x<...")
** If score&2 is not 0 then there is an inequality used as the
** start key. (ex: "x>..."). A score or 4 is the special case
** of an IN operator constraint. (ex: "x IN ...").
**
** The IN operator (as in "<expr> IN (...)") is treated the same as
** an equality comparison except that it can only be used on the
** left-most column of an index and other terms of the WHERE clause
** cannot be used in conjunction with the IN operator to help satisfy
** other columns of the index.
*/
for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
int eqMask = 0; /* Index columns covered by an x=... term */
int ltMask = 0; /* Index columns covered by an x<... term */
int gtMask = 0; /* Index columns covered by an x>... term */
int inMask = 0; /* Index columns covered by an x IN .. term */
int nEq, m, score;
if( pIdx->nColumn>32 ) continue; /* Ignore indices too many columns */
for(j=0; j<nExpr; j++){
if( aExpr[j].idxLeft==iCur
&& (aExpr[j].prereqRight & loopMask)==aExpr[j].prereqRight ){
int iColumn = aExpr[j].p->pLeft->iColumn;
int k;
for(k=0; k<pIdx->nColumn; k++){
if( pIdx->aiColumn[k]==iColumn ){
switch( aExpr[j].p->op ){
case TK_IN: {
if( k==0 ) inMask |= 1;
break;
}
case TK_EQ: {
eqMask |= 1<<k;
break;
}
case TK_LE:
case TK_LT: {
ltMask |= 1<<k;
break;
}
case TK_GE:
case TK_GT: {
gtMask |= 1<<k;
break;
}
default: {
/* CANT_HAPPEN */
assert( 0 );
break;
}
}
break;
}
}
}
if( aExpr[j].idxRight==iCur
&& (aExpr[j].prereqLeft & loopMask)==aExpr[j].prereqLeft ){
int iColumn = aExpr[j].p->pRight->iColumn;
int k;
for(k=0; k<pIdx->nColumn; k++){
if( pIdx->aiColumn[k]==iColumn ){
switch( aExpr[j].p->op ){
case TK_EQ: {
eqMask |= 1<<k;
break;
}
case TK_LE:
case TK_LT: {
gtMask |= 1<<k;
break;
}
case TK_GE:
case TK_GT: {
ltMask |= 1<<k;
break;
}
default: {
/* CANT_HAPPEN */
assert( 0 );
break;
}
}
break;
}
}
}
}
/* The following loop ends with nEq set to the number of columns
** on the left of the index with == constraints.
*/
for(nEq=0; nEq<pIdx->nColumn; nEq++){
m = (1<<(nEq+1))-1;
if( (m & eqMask)!=m ) break;
}
score = nEq*8; /* Base score is 8 times number of == constraints */
m = 1<<nEq;
if( m & ltMask ) score++; /* Increase score for a < constraint */
if( m & gtMask ) score+=2; /* Increase score for a > constraint */
if( score==0 && inMask ) score = 4; /* Default score for IN constraint */
if( score>bestScore ){
pBestIdx = pIdx;
bestScore = score;
}
}
pWInfo->a[i].pIdx = pBestIdx;
pWInfo->a[i].score = bestScore;
pWInfo->a[i].bRev = 0;
loopMask |= mask;
if( pBestIdx ){
pWInfo->a[i].iCur = pParse->nTab++;
pWInfo->peakNTab = pParse->nTab;
}
}
/* Check to see if the ORDER BY clause is or can be satisfied by the
** use of an index on the first table.
*/
if( ppOrderBy && *ppOrderBy && pTabList->nSrc>0 ){
Index *pSortIdx;
Index *pIdx;
Table *pTab;
int bRev = 0;
pTab = pTabList->a[0].pTab;
pIdx = pWInfo->a[0].pIdx;
if( pIdx && pWInfo->a[0].score==4 ){
/* If there is already an IN index on the left-most table,
** it will not give the correct sort order.
** So, pretend that no suitable index is found.
*/
pSortIdx = 0;
}else if( iDirectEq[0]>=0 || iDirectLt[0]>=0 || iDirectGt[0]>=0 ){
/* If the left-most column is accessed using its ROWID, then do
** not try to sort by index.
*/
pSortIdx = 0;
}else{
int nEqCol = (pWInfo->a[0].score+4)/8;
pSortIdx = findSortingIndex(pTab, pTabList->a[0].iCursor,
*ppOrderBy, pIdx, nEqCol, &bRev);
}
if( pSortIdx && (pIdx==0 || pIdx==pSortIdx) ){
if( pIdx==0 ){
pWInfo->a[0].pIdx = pSortIdx;
pWInfo->a[0].iCur = pParse->nTab++;
pWInfo->peakNTab = pParse->nTab;
}
pWInfo->a[0].bRev = bRev;
*ppOrderBy = 0;
}
}
/* Open all tables in the pTabList and all indices used by those tables.
*/
for(i=0; i<pTabList->nSrc; i++){
Table *pTab;
Index *pIx;
pTab = pTabList->a[i].pTab;
if( pTab->isTransient || pTab->pSelect ) continue;
sqliteVdbeAddOp(v, OP_Integer, pTab->iDb, 0);
sqliteVdbeOp3(v, OP_OpenRead, pTabList->a[i].iCursor, pTab->tnum,
pTab->zName, P3_STATIC);
sqliteCodeVerifySchema(pParse, pTab->iDb);
if( (pIx = pWInfo->a[i].pIdx)!=0 ){
sqliteVdbeAddOp(v, OP_Integer, pIx->iDb, 0);
sqliteVdbeOp3(v, OP_OpenRead, pWInfo->a[i].iCur, pIx->tnum, pIx->zName,0);
}
}
/* Generate the code to do the search
*/
loopMask = 0;
for(i=0; i<pTabList->nSrc; i++){
int j, k;
int iCur = pTabList->a[i].iCursor;
Index *pIdx;
WhereLevel *pLevel = &pWInfo->a[i];
/* If this is the right table of a LEFT OUTER JOIN, allocate and
** initialize a memory cell that records if this table matches any
** row of the left table of the join.
*/
if( i>0 && (pTabList->a[i-1].jointype & JT_LEFT)!=0 ){
if( !pParse->nMem ) pParse->nMem++;
pLevel->iLeftJoin = pParse->nMem++;
sqliteVdbeAddOp(v, OP_String, 0, 0);
sqliteVdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1);
}
pIdx = pLevel->pIdx;
pLevel->inOp = OP_Noop;
if( i<ARRAYSIZE(iDirectEq) && iDirectEq[i]>=0 ){
/* Case 1: We can directly reference a single row using an
** equality comparison against the ROWID field. Or
** we reference multiple rows using a "rowid IN (...)"
** construct.
*/
k = iDirectEq[i];
assert( k<nExpr );
assert( aExpr[k].p!=0 );
assert( aExpr[k].idxLeft==iCur || aExpr[k].idxRight==iCur );
brk = pLevel->brk = sqliteVdbeMakeLabel(v);
if( aExpr[k].idxLeft==iCur ){
Expr *pX = aExpr[k].p;
if( pX->op!=TK_IN ){
sqliteExprCode(pParse, aExpr[k].p->pRight);
}else if( pX->pList ){
sqliteVdbeAddOp(v, OP_SetFirst, pX->iTable, brk);
pLevel->inOp = OP_SetNext;
pLevel->inP1 = pX->iTable;
pLevel->inP2 = sqliteVdbeCurrentAddr(v);
}else{
assert( pX->pSelect );
sqliteVdbeAddOp(v, OP_Rewind, pX->iTable, brk);
sqliteVdbeAddOp(v, OP_KeyAsData, pX->iTable, 1);
pLevel->inP2 = sqliteVdbeAddOp(v, OP_FullKey, pX->iTable, 0);
pLevel->inOp = OP_Next;
pLevel->inP1 = pX->iTable;
}
}else{
sqliteExprCode(pParse, aExpr[k].p->pLeft);
}
disableTerm(pLevel, &aExpr[k].p);
cont = pLevel->cont = sqliteVdbeMakeLabel(v);
sqliteVdbeAddOp(v, OP_MustBeInt, 1, brk);
haveKey = 0;
sqliteVdbeAddOp(v, OP_NotExists, iCur, brk);
pLevel->op = OP_Noop;
}else if( pIdx!=0 && pLevel->score>0 && pLevel->score%4==0 ){
/* Case 2: There is an index and all terms of the WHERE clause that
** refer to the index use the "==" or "IN" operators.
*/
int start;
int testOp;
int nColumn = (pLevel->score+4)/8;
brk = pLevel->brk = sqliteVdbeMakeLabel(v);
for(j=0; j<nColumn; j++){
for(k=0; k<nExpr; k++){
Expr *pX = aExpr[k].p;
if( pX==0 ) continue;
if( aExpr[k].idxLeft==iCur
&& (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight
&& pX->pLeft->iColumn==pIdx->aiColumn[j]
){
if( pX->op==TK_EQ ){
sqliteExprCode(pParse, pX->pRight);
disableTerm(pLevel, &aExpr[k].p);
break;
}
if( pX->op==TK_IN && nColumn==1 ){
if( pX->pList ){
sqliteVdbeAddOp(v, OP_SetFirst, pX->iTable, brk);
pLevel->inOp = OP_SetNext;
pLevel->inP1 = pX->iTable;
pLevel->inP2 = sqliteVdbeCurrentAddr(v);
}else{
assert( pX->pSelect );
sqliteVdbeAddOp(v, OP_Rewind, pX->iTable, brk);
sqliteVdbeAddOp(v, OP_KeyAsData, pX->iTable, 1);
pLevel->inP2 = sqliteVdbeAddOp(v, OP_FullKey, pX->iTable, 0);
pLevel->inOp = OP_Next;
pLevel->inP1 = pX->iTable;
}
disableTerm(pLevel, &aExpr[k].p);
break;
}
}
if( aExpr[k].idxRight==iCur
&& aExpr[k].p->op==TK_EQ
&& (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
&& aExpr[k].p->pRight->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, aExpr[k].p->pLeft);
disableTerm(pLevel, &aExpr[k].p);
break;
}
}
}
pLevel->iMem = pParse->nMem++;
cont = pLevel->cont = sqliteVdbeMakeLabel(v);
sqliteVdbeAddOp(v, OP_NotNull, -nColumn, sqliteVdbeCurrentAddr(v)+3);
sqliteVdbeAddOp(v, OP_Pop, nColumn, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, brk);
sqliteVdbeAddOp(v, OP_MakeKey, nColumn, 0);
sqliteAddIdxKeyType(v, pIdx);
if( nColumn==pIdx->nColumn || pLevel->bRev ){
sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 0);
testOp = OP_IdxGT;
}else{
sqliteVdbeAddOp(v, OP_Dup, 0, 0);
sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
testOp = OP_IdxGE;
}
if( pLevel->bRev ){
/* Scan in reverse order */
sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
sqliteVdbeAddOp(v, OP_MoveLt, pLevel->iCur, brk);
start = sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
sqliteVdbeAddOp(v, OP_IdxLT, pLevel->iCur, brk);
pLevel->op = OP_Prev;
}else{
/* Scan in the forward order */
sqliteVdbeAddOp(v, OP_MoveTo, pLevel->iCur, brk);
start = sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
sqliteVdbeAddOp(v, testOp, pLevel->iCur, brk);
pLevel->op = OP_Next;
}
sqliteVdbeAddOp(v, OP_RowKey, pLevel->iCur, 0);
sqliteVdbeAddOp(v, OP_IdxIsNull, nColumn, cont);
sqliteVdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0);
if( i==pTabList->nSrc-1 && pushKey ){
haveKey = 1;
}else{
sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
haveKey = 0;
}
pLevel->p1 = pLevel->iCur;
pLevel->p2 = start;
}else if( i<ARRAYSIZE(iDirectLt) && (iDirectLt[i]>=0 || iDirectGt[i]>=0) ){
/* Case 3: We have an inequality comparison against the ROWID field.
*/
int testOp = OP_Noop;
int start;
brk = pLevel->brk = sqliteVdbeMakeLabel(v);
cont = pLevel->cont = sqliteVdbeMakeLabel(v);
if( iDirectGt[i]>=0 ){
k = iDirectGt[i];
assert( k<nExpr );
assert( aExpr[k].p!=0 );
assert( aExpr[k].idxLeft==iCur || aExpr[k].idxRight==iCur );
if( aExpr[k].idxLeft==iCur ){
sqliteExprCode(pParse, aExpr[k].p->pRight);
}else{
sqliteExprCode(pParse, aExpr[k].p->pLeft);
}
sqliteVdbeAddOp(v, OP_ForceInt,
aExpr[k].p->op==TK_LT || aExpr[k].p->op==TK_GT, brk);
sqliteVdbeAddOp(v, OP_MoveTo, iCur, brk);
disableTerm(pLevel, &aExpr[k].p);
}else{
sqliteVdbeAddOp(v, OP_Rewind, iCur, brk);
}
if( iDirectLt[i]>=0 ){
k = iDirectLt[i];
assert( k<nExpr );
assert( aExpr[k].p!=0 );
assert( aExpr[k].idxLeft==iCur || aExpr[k].idxRight==iCur );
if( aExpr[k].idxLeft==iCur ){
sqliteExprCode(pParse, aExpr[k].p->pRight);
}else{
sqliteExprCode(pParse, aExpr[k].p->pLeft);
}
/* sqliteVdbeAddOp(v, OP_MustBeInt, 0, sqliteVdbeCurrentAddr(v)+1); */
pLevel->iMem = pParse->nMem++;
sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
if( aExpr[k].p->op==TK_LT || aExpr[k].p->op==TK_GT ){
testOp = OP_Ge;
}else{
testOp = OP_Gt;
}
disableTerm(pLevel, &aExpr[k].p);
}
start = sqliteVdbeCurrentAddr(v);
pLevel->op = OP_Next;
pLevel->p1 = iCur;
pLevel->p2 = start;
if( testOp!=OP_Noop ){
sqliteVdbeAddOp(v, OP_Recno, iCur, 0);
sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
sqliteVdbeAddOp(v, testOp, 0, brk);
}
haveKey = 0;
}else if( pIdx==0 ){
/* Case 4: There is no usable index. We must do a complete
** scan of the entire database table.
*/
int start;
brk = pLevel->brk = sqliteVdbeMakeLabel(v);
cont = pLevel->cont = sqliteVdbeMakeLabel(v);
sqliteVdbeAddOp(v, OP_Rewind, iCur, brk);
start = sqliteVdbeCurrentAddr(v);
pLevel->op = OP_Next;
pLevel->p1 = iCur;
pLevel->p2 = start;
haveKey = 0;
}else{
/* Case 5: The WHERE clause term that refers to the right-most
** column of the index is an inequality. For example, if
** the index is on (x,y,z) and the WHERE clause is of the
** form "x=5 AND y<10" then this case is used. Only the
** right-most column can be an inequality - the rest must
** use the "==" operator.
**
** This case is also used when there are no WHERE clause
** constraints but an index is selected anyway, in order
** to force the output order to conform to an ORDER BY.
*/
int score = pLevel->score;
int nEqColumn = score/8;
int start;
int leFlag, geFlag;
int testOp;
/* Evaluate the equality constraints
*/
for(j=0; j<nEqColumn; j++){
for(k=0; k<nExpr; k++){
if( aExpr[k].p==0 ) continue;
if( aExpr[k].idxLeft==iCur
&& aExpr[k].p->op==TK_EQ
&& (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight
&& aExpr[k].p->pLeft->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, aExpr[k].p->pRight);
disableTerm(pLevel, &aExpr[k].p);
break;
}
if( aExpr[k].idxRight==iCur
&& aExpr[k].p->op==TK_EQ
&& (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
&& aExpr[k].p->pRight->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, aExpr[k].p->pLeft);
disableTerm(pLevel, &aExpr[k].p);
break;
}
}
}
/* Duplicate the equality term values because they will all be
** used twice: once to make the termination key and once to make the
** start key.
*/
for(j=0; j<nEqColumn; j++){
sqliteVdbeAddOp(v, OP_Dup, nEqColumn-1, 0);
}
/* Labels for the beginning and end of the loop
*/
cont = pLevel->cont = sqliteVdbeMakeLabel(v);
brk = pLevel->brk = sqliteVdbeMakeLabel(v);
/* Generate the termination key. This is the key value that
** will end the search. There is no termination key if there
** are no equality terms and no "X<..." term.
**
** 2002-Dec-04: On a reverse-order scan, the so-called "termination"
** key computed here really ends up being the start key.
*/
if( (score & 1)!=0 ){
for(k=0; k<nExpr; k++){
Expr *pExpr = aExpr[k].p;
if( pExpr==0 ) continue;
if( aExpr[k].idxLeft==iCur
&& (pExpr->op==TK_LT || pExpr->op==TK_LE)
&& (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight
&& pExpr->pLeft->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, pExpr->pRight);
leFlag = pExpr->op==TK_LE;
disableTerm(pLevel, &aExpr[k].p);
break;
}
if( aExpr[k].idxRight==iCur
&& (pExpr->op==TK_GT || pExpr->op==TK_GE)
&& (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
&& pExpr->pRight->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, pExpr->pLeft);
leFlag = pExpr->op==TK_GE;
disableTerm(pLevel, &aExpr[k].p);
break;
}
}
testOp = OP_IdxGE;
}else{
testOp = nEqColumn>0 ? OP_IdxGE : OP_Noop;
leFlag = 1;
}
if( testOp!=OP_Noop ){
int nCol = nEqColumn + (score & 1);
pLevel->iMem = pParse->nMem++;
sqliteVdbeAddOp(v, OP_NotNull, -nCol, sqliteVdbeCurrentAddr(v)+3);
sqliteVdbeAddOp(v, OP_Pop, nCol, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, brk);
sqliteVdbeAddOp(v, OP_MakeKey, nCol, 0);
sqliteAddIdxKeyType(v, pIdx);
if( leFlag ){
sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
}
if( pLevel->bRev ){
sqliteVdbeAddOp(v, OP_MoveLt, pLevel->iCur, brk);
}else{
sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
}
}else if( pLevel->bRev ){
sqliteVdbeAddOp(v, OP_Last, pLevel->iCur, brk);
}
/* Generate the start key. This is the key that defines the lower
** bound on the search. There is no start key if there are no
** equality terms and if there is no "X>..." term. In
** that case, generate a "Rewind" instruction in place of the
** start key search.
**
** 2002-Dec-04: In the case of a reverse-order search, the so-called
** "start" key really ends up being used as the termination key.
*/
if( (score & 2)!=0 ){
for(k=0; k<nExpr; k++){
Expr *pExpr = aExpr[k].p;
if( pExpr==0 ) continue;
if( aExpr[k].idxLeft==iCur
&& (pExpr->op==TK_GT || pExpr->op==TK_GE)
&& (aExpr[k].prereqRight & loopMask)==aExpr[k].prereqRight
&& pExpr->pLeft->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, pExpr->pRight);
geFlag = pExpr->op==TK_GE;
disableTerm(pLevel, &aExpr[k].p);
break;
}
if( aExpr[k].idxRight==iCur
&& (pExpr->op==TK_LT || pExpr->op==TK_LE)
&& (aExpr[k].prereqLeft & loopMask)==aExpr[k].prereqLeft
&& pExpr->pRight->iColumn==pIdx->aiColumn[j]
){
sqliteExprCode(pParse, pExpr->pLeft);
geFlag = pExpr->op==TK_LE;
disableTerm(pLevel, &aExpr[k].p);
break;
}
}
}else{
geFlag = 1;
}
if( nEqColumn>0 || (score&2)!=0 ){
int nCol = nEqColumn + ((score&2)!=0);
sqliteVdbeAddOp(v, OP_NotNull, -nCol, sqliteVdbeCurrentAddr(v)+3);
sqliteVdbeAddOp(v, OP_Pop, nCol, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, brk);
sqliteVdbeAddOp(v, OP_MakeKey, nCol, 0);
sqliteAddIdxKeyType(v, pIdx);
if( !geFlag ){
sqliteVdbeAddOp(v, OP_IncrKey, 0, 0);
}
if( pLevel->bRev ){
pLevel->iMem = pParse->nMem++;
sqliteVdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
testOp = OP_IdxLT;
}else{
sqliteVdbeAddOp(v, OP_MoveTo, pLevel->iCur, brk);
}
}else if( pLevel->bRev ){
testOp = OP_Noop;
}else{
sqliteVdbeAddOp(v, OP_Rewind, pLevel->iCur, brk);
}
/* Generate the the top of the loop. If there is a termination
** key we have to test for that key and abort at the top of the
** loop.
*/
start = sqliteVdbeCurrentAddr(v);
if( testOp!=OP_Noop ){
sqliteVdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
sqliteVdbeAddOp(v, testOp, pLevel->iCur, brk);
}
sqliteVdbeAddOp(v, OP_RowKey, pLevel->iCur, 0);
sqliteVdbeAddOp(v, OP_IdxIsNull, nEqColumn + (score & 1), cont);
sqliteVdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0);
if( i==pTabList->nSrc-1 && pushKey ){
haveKey = 1;
}else{
sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
haveKey = 0;
}
/* Record the instruction used to terminate the loop.
*/
pLevel->op = pLevel->bRev ? OP_Prev : OP_Next;
pLevel->p1 = pLevel->iCur;
pLevel->p2 = start;
}
loopMask |= getMask(&maskSet, iCur);
/* Insert code to test every subexpression that can be completely
** computed using the current set of tables.
*/
for(j=0; j<nExpr; j++){
if( aExpr[j].p==0 ) continue;
if( (aExpr[j].prereqAll & loopMask)!=aExpr[j].prereqAll ) continue;
if( pLevel->iLeftJoin && !ExprHasProperty(aExpr[j].p,EP_FromJoin) ){
continue;
}
if( haveKey ){
haveKey = 0;
sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
}
sqliteExprIfFalse(pParse, aExpr[j].p, cont, 1);
aExpr[j].p = 0;
}
brk = cont;
/* For a LEFT OUTER JOIN, generate code that will record the fact that
** at least one row of the right table has matched the left table.
*/
if( pLevel->iLeftJoin ){
pLevel->top = sqliteVdbeCurrentAddr(v);
sqliteVdbeAddOp(v, OP_Integer, 1, 0);
sqliteVdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1);
for(j=0; j<nExpr; j++){
if( aExpr[j].p==0 ) continue;
if( (aExpr[j].prereqAll & loopMask)!=aExpr[j].prereqAll ) continue;
if( haveKey ){
/* Cannot happen. "haveKey" can only be true if pushKey is true
** an pushKey can only be true for DELETE and UPDATE and there are
** no outer joins with DELETE and UPDATE.
*/
haveKey = 0;
sqliteVdbeAddOp(v, OP_MoveTo, iCur, 0);
}
sqliteExprIfFalse(pParse, aExpr[j].p, cont, 1);
aExpr[j].p = 0;
}
}
}
pWInfo->iContinue = cont;
if( pushKey && !haveKey ){
sqliteVdbeAddOp(v, OP_Recno, pTabList->a[0].iCursor, 0);
}
freeMaskSet(&maskSet);
return pWInfo;
}
/*
** This routine walks an expression tree and resolves references to
** table columns. Nodes of the form ID.ID or ID resolve into an
** index to the table in the table list and a column offset. The
** Expr.opcode for such nodes is changed to TK_COLUMN. The Expr.iTable
** value is changed to the index of the referenced table in pTabList
** plus the "base" value. The base value will ultimately become the
** VDBE cursor number for a cursor that is pointing into the referenced
** table. The Expr.iColumn value is changed to the index of the column
** of the referenced table. The Expr.iColumn value for the special
** ROWID column is -1. Any INTEGER PRIMARY KEY column is tried as an
** alias for ROWID.
**
** We also check for instances of the IN operator. IN comes in two
** forms:
**
** expr IN (exprlist)
** and
** expr IN (SELECT ...)
**
** The first form is handled by creating a set holding the list
** of allowed values. The second form causes the SELECT to generate
** a temporary table.
**
** This routine also looks for scalar SELECTs that are part of an expression.
** If it finds any, it generates code to write the value of that select
** into a memory cell.
**
** Unknown columns or tables provoke an error. The function returns
** the number of errors seen and leaves an error message on pParse->zErrMsg.
*/
int sqliteExprResolveIds(
Parse *pParse, /* The parser context */
SrcList *pSrcList, /* List of tables used to resolve column names */
ExprList *pEList, /* List of expressions used to resolve "AS" */
Expr *pExpr /* The expression to be analyzed. */
){
int i;
if( pExpr==0 || pSrcList==0 ) return 0;
for(i=0; i<pSrcList->nSrc; i++){
assert( pSrcList->a[i].iCursor>=0 && pSrcList->a[i].iCursor<pParse->nTab );
}
switch( pExpr->op ){
/* Double-quoted strings (ex: "abc") are used as identifiers if
** possible. Otherwise they remain as strings. Single-quoted
** strings (ex: 'abc') are always string literals.
*/
case TK_STRING: {
if( pExpr->token.z[0]=='\'' ) break;
/* Fall thru into the TK_ID case if this is a double-quoted string */
}
/* A lone identifier is the name of a columnd.
*/
case TK_ID: {
if( lookupName(pParse, 0, 0, &pExpr->token, pSrcList, pEList, pExpr) ){
return 1;
}
break;
}
/* A table name and column name: ID.ID
** Or a database, table and column: ID.ID.ID
*/
case TK_DOT: {
Token *pColumn;
Token *pTable;
Token *pDb;
Expr *pRight;
pRight = pExpr->pRight;
if( pRight->op==TK_ID ){
pDb = 0;
pTable = &pExpr->pLeft->token;
pColumn = &pRight->token;
}else{
assert( pRight->op==TK_DOT );
pDb = &pExpr->pLeft->token;
pTable = &pRight->pLeft->token;
pColumn = &pRight->pRight->token;
}
if( lookupName(pParse, pDb, pTable, pColumn, pSrcList, 0, pExpr) ){
return 1;
}
break;
}
case TK_IN: {
Vdbe *v = sqliteGetVdbe(pParse);
if( v==0 ) return 1;
if( sqliteExprResolveIds(pParse, pSrcList, pEList, pExpr->pLeft) ){
return 1;
}
if( pExpr->pSelect ){
/* Case 1: expr IN (SELECT ...)
**
** Generate code to write the results of the select into a temporary
** table. The cursor number of the temporary table has already
** been put in iTable by sqliteExprResolveInSelect().
*/
pExpr->iTable = pParse->nTab++;
sqliteVdbeAddOp(v, OP_OpenTemp, pExpr->iTable, 1);
sqliteSelect(pParse, pExpr->pSelect, SRT_Set, pExpr->iTable, 0,0,0);
}else if( pExpr->pList ){
/* Case 2: expr IN (exprlist)
**
** Create a set to put the exprlist values in. The Set id is stored
** in iTable.
*/
int i, iSet;
for(i=0; i<pExpr->pList->nExpr; i++){
Expr *pE2 = pExpr->pList->a[i].pExpr;
if( !sqliteExprIsConstant(pE2) ){
sqliteErrorMsg(pParse,
"right-hand side of IN operator must be constant");
return 1;
}
if( sqliteExprCheck(pParse, pE2, 0, 0) ){
return 1;
}
}
iSet = pExpr->iTable = pParse->nSet++;
for(i=0; i<pExpr->pList->nExpr; i++){
Expr *pE2 = pExpr->pList->a[i].pExpr;
switch( pE2->op ){
case TK_FLOAT:
case TK_INTEGER:
case TK_STRING: {
int addr;
assert( pE2->token.z );
addr = sqliteVdbeOp3(v, OP_SetInsert, iSet, 0,
pE2->token.z, pE2->token.n);
sqliteVdbeDequoteP3(v, addr);
break;
}
default: {
sqliteExprCode(pParse, pE2);
sqliteVdbeAddOp(v, OP_SetInsert, iSet, 0);
break;
}
}
}
}
break;
}
case TK_SELECT: {
/* This has to be a scalar SELECT. Generate code to put the
** value of this select in a memory cell and record the number
** of the memory cell in iColumn.
*/
pExpr->iColumn = pParse->nMem++;
if( sqliteSelect(pParse, pExpr->pSelect, SRT_Mem, pExpr->iColumn,0,0,0) ){
return 1;
}
break;
}
/* For all else, just recursively walk the tree */
default: {
if( pExpr->pLeft
&& sqliteExprResolveIds(pParse, pSrcList, pEList, pExpr->pLeft) ){
return 1;
}
if( pExpr->pRight
&& sqliteExprResolveIds(pParse, pSrcList, pEList, pExpr->pRight) ){
return 1;
}
if( pExpr->pList ){
int i;
ExprList *pList = pExpr->pList;
for(i=0; i<pList->nExpr; i++){
Expr *pArg = pList->a[i].pExpr;
if( sqliteExprResolveIds(pParse, pSrcList, pEList, pArg) ){
return 1;
}
}
}
}
}
return 0;
}
