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Minor enhancements to comments and clarification of the code.

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FossilOrigin-Name: cbec30d0c49a3f618c3df3ae0ca3d651b48841c2
This commit is contained in:
drh
2014-05-26 22:01:00 +00:00
parent 68c121534c
commit 5609baf35e
3 changed files with 17 additions and 15 deletions
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18
src/where.c
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@@ -3293,6 +3293,10 @@ static Bitmask codeOneLoopStart(
**
** B: <after the loop>
**
** Added 2014-05-26: If the table is a WITHOUT ROWID table, then
** use an ephermeral index instead of a RowSet to record the primary
** keys of the rows we have already seen.
**
*/
WhereClause *pOrWc; /* The OR-clause broken out into subterms */
SrcList *pOrTab; /* Shortened table list or OR-clause generation */
@@ -3340,7 +3344,8 @@ static Bitmask codeOneLoopStart(
}
/* Initialize the rowset register to contain NULL. An SQL NULL is
** equivalent to an empty rowset.
** equivalent to an empty rowset. Or, create an ephermeral index
** capable of holding primary keys in the case of a WITHOUT ROWID.
**
** Also initialize regReturn to contain the address of the instruction
** immediately following the OP_Return at the bottom of the loop. This
@@ -3401,6 +3406,7 @@ static Bitmask codeOneLoopStart(
if( pOrTerm->leftCursor==iCur || (pOrTerm->eOperator & WO_AND)!=0 ){
WhereInfo *pSubWInfo; /* Info for single OR-term scan */
Expr *pOrExpr = pOrTerm->pExpr;
int j1 = 0; /* Address of jump operation */
if( pAndExpr && !ExprHasProperty(pOrExpr, EP_FromJoin) ){
pAndExpr->pLeft = pOrExpr;
pOrExpr = pAndExpr;
@@ -3417,12 +3423,10 @@ static Bitmask codeOneLoopStart(
);
if( (pWInfo->wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
int r;
int addr; /* Address just past Gosub coded below */
int iSet = ((ii==pOrWc->nTerm-1)?-1:ii);
if( HasRowid(pTab) ){
r = sqlite3ExprCodeGetColumn(pParse, pTab, -1, iCur, regRowid, 0);
addr = sqlite3VdbeCurrentAddr(v)+2;
sqlite3VdbeAddOp4Int(v, OP_RowSetTest, regRowset, addr, r, iSet);
j1 = sqlite3VdbeAddOp4Int(v, OP_RowSetTest, regRowset, 0, r,iSet);
VdbeCoverage(v);
}else{
Index *pPk = sqlite3PrimaryKeyIndex(pTab);
@@ -3448,8 +3452,7 @@ static Bitmask codeOneLoopStart(
** need to insert the key into the temp table, as it will never
** be tested for. */
if( iSet ){
addr = sqlite3VdbeCurrentAddr(v) + 2 + ((iSet>0) ? 2 : 0);
sqlite3VdbeAddOp4Int(v, OP_Found, regRowset, addr, r, nPk);
j1 = sqlite3VdbeAddOp4Int(v, OP_Found, regRowset, 0, r, nPk);
VdbeCoverage(v);
}
if( iSet>=0 ){
@@ -3461,10 +3464,9 @@ static Bitmask codeOneLoopStart(
/* Release the array of temp registers */
sqlite3ReleaseTempRange(pParse, r, nPk);
}
assert( db->mallocFailed
|| iSet==0 || addr==(sqlite3VdbeCurrentAddr(v)+1) );
}
sqlite3VdbeAddOp2(v, OP_Gosub, regReturn, iLoopBody);
if( j1 ) sqlite3VdbeJumpHere(v, j1);
/* The pSubWInfo->untestedTerms flag means that this OR term
** contained one or more AND term from a notReady table. The