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Refactoring of DISTINCT code. Change the name of the local variable

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"distinct" to "distinctTab".  Generate cleaner code w/o unnecessary P4
and P5 values on the OP_Null for WHERE_DISTINCT_ORDERED.

FossilOrigin-Name: 0cda241a2bcb3c6f2ae6c48f522780bc4eddfc02
This commit is contained in:
drh
2012-09-20 14:26:22 +00:00
parent 053a128f55
commit 2c79733f3c
4 changed files with 22 additions and 24 deletions
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28
src/select.c
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@@ -541,7 +541,7 @@ static void selectInnerLoop(
int srcTab, /* Pull data from this table */
int nColumn, /* Number of columns in the source table */
ExprList *pOrderBy, /* If not NULL, sort results using this key */
int distinct, /* If >=0, make sure results are distinct */
int distinctTab, /* If >=0, make sure results are distinct */
SelectDest *pDest, /* How to dispose of the results */
int iContinue, /* Jump here to continue with next row */
int iBreak /* Jump here to break out of the inner loop */
@@ -557,7 +557,7 @@ static void selectInnerLoop(
assert( v );
if( NEVER(v==0) ) return;
assert( pEList!=0 );
hasDistinct = distinct>=0;
hasDistinct = distinctTab>=0;
if( pOrderBy==0 && !hasDistinct ){
codeOffset(v, p, iContinue);
}
@@ -597,7 +597,7 @@ static void selectInnerLoop(
if( hasDistinct ){
assert( pEList!=0 );
assert( pEList->nExpr==nColumn );
codeDistinct(pParse, distinct, iContinue, nColumn, regResult);
codeDistinct(pParse, distinctTab, iContinue, nColumn, regResult);
if( pOrderBy==0 ){
codeOffset(v, p, iContinue);
}
@@ -3787,7 +3787,7 @@ int sqlite3Select(
ExprList *pGroupBy; /* The GROUP BY clause. May be NULL */
Expr *pHaving; /* The HAVING clause. May be NULL */
int isDistinct; /* True if the DISTINCT keyword is present */
int distinct; /* Table to use for the distinct set */
int distinctTab; /* Table to use for the distinct set */
int rc = 1; /* Value to return from this function */
int addrSortIndex; /* Address of an OP_OpenEphemeral instruction */
int addrDistinctIndex; /* Address of an OP_OpenEphemeral instruction */
@@ -4018,13 +4018,13 @@ int sqlite3Select(
*/
if( p->selFlags & SF_Distinct ){
KeyInfo *pKeyInfo;
distinct = pParse->nTab++;
distinctTab = pParse->nTab++;
pKeyInfo = keyInfoFromExprList(pParse, p->pEList);
addrDistinctIndex = sqlite3VdbeAddOp4(v, OP_OpenEphemeral, distinct, 0, 0,
(char*)pKeyInfo, P4_KEYINFO_HANDOFF);
addrDistinctIndex = sqlite3VdbeAddOp4(v, OP_OpenEphemeral, distinctTab,
0, 0, (char*)pKeyInfo, P4_KEYINFO_HANDOFF);
sqlite3VdbeChangeP5(v, BTREE_UNORDERED);
}else{
distinct = addrDistinctIndex = -1;
distinctTab = addrDistinctIndex = -1;
}
/* Aggregate and non-aggregate queries are handled differently */
@@ -4049,13 +4049,14 @@ int sqlite3Select(
VdbeOp *pOp; /* No longer required OpenEphemeral instr. */
assert( addrDistinctIndex>=0 );
sqlite3VdbeChangeToNoop(v, addrDistinctIndex);
pOp = sqlite3VdbeGetOp(v, addrDistinctIndex);
assert( isDistinct );
assert( pWInfo->eDistinct==WHERE_DISTINCT_ORDERED
|| pWInfo->eDistinct==WHERE_DISTINCT_UNIQUE
);
distinct = -1;
distinctTab = -1;
if( pWInfo->eDistinct==WHERE_DISTINCT_ORDERED ){
int iJump;
int iExpr;
@@ -4073,7 +4074,6 @@ int sqlite3Select(
pOp->opcode = OP_Null;
pOp->p1 = 1;
pOp->p2 = iBase2;
pOp->p3 = iBase2 + nExpr - 1;
sqlite3ExprCodeExprList(pParse, pEList, iBase, 1);
iJump = sqlite3VdbeCurrentAddr(v) + pEList->nExpr;
@@ -4090,13 +4090,11 @@ int sqlite3Select(
}
assert( sqlite3VdbeCurrentAddr(v)==iJump );
sqlite3VdbeAddOp3(v, OP_Move, iBase, iBase2, pEList->nExpr);
}else{
pOp->opcode = OP_Noop;
}
}
/* Use the standard inner loop. */
selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinct, pDest,
selectInnerLoop(pParse, p, pEList, 0, 0, pOrderBy, distinctTab, pDest,
pWInfo->iContinue, pWInfo->iBreak);
/* End the database scan loop.
@@ -4364,7 +4362,7 @@ int sqlite3Select(
finalizeAggFunctions(pParse, &sAggInfo);
sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
selectInnerLoop(pParse, p, p->pEList, 0, 0, pOrderBy,
distinct, pDest,
distinctTab, pDest,
addrOutputRow+1, addrSetAbort);
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
VdbeComment((v, "end groupby result generator"));
@@ -4505,7 +4503,7 @@ int sqlite3Select(
} /* endif aggregate query */
if( distinct>=0 ){
if( distinctTab>=0 ){
explainTempTable(pParse, "DISTINCT");
}