aboutsummaryrefslogtreecommitdiff
path: root/src/select.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/select.c')
-rw-r--r--src/select.c271
1 files changed, 188 insertions, 83 deletions
diff --git a/src/select.c b/src/select.c
index cab90eb01..b94efd5f3 100644
--- a/src/select.c
+++ b/src/select.c
@@ -741,31 +741,146 @@ static void codeOffset(
}
/*
-** Add code that will check to make sure the N registers starting at iMem
-** form a distinct entry. iTab is a sorting index that holds previously
-** seen combinations of the N values. A new entry is made in iTab
-** if the current N values are new.
-**
-** A jump to addrRepeat is made and the N+1 values are popped from the
-** stack if the top N elements are not distinct.
+** Add code that will check to make sure the array of registers starting at
+** iMem form a distinct entry. This is used by both "SELECT DISTINCT ..." and
+** distinct aggregates ("SELECT count(DISTINCT <expr>) ..."). Three strategies
+** are available. Which is used depends on the value of parameter eTnctType,
+** as follows:
+**
+** WHERE_DISTINCT_UNORDERED/WHERE_DISTINCT_NOOP:
+** Parameter iTab is the cursor number of an ephemeral table that must
+** be opened before the VM code generated by this routine is executed.
+** The ephemeral cursor table is queried for a record identical to the
+** record formed by the current array of registers. If one is found,
+** jump to VM address addrRepeat. Otherwise, insert a new record into
+** the ephemeral cursor and proceed.
+**
+** The returned value in this case is a copy of parameter iTab.
+**
+** WHERE_DISTINCT_ORDERED:
+** In this case rows are being delivered sorted order sorted. The ephermal
+** table is not required in this case. Instead, the current set of
+** registers are compared to previous row. If they match, the new row
+** is not distinct and control jumps to VM address addrRepeat. Otherwise,
+** the VM program proceeds with processing the new row.
+**
+** The returned value in this case is the register number of the first
+** in an array of registers used to store the previous result row so that
+** it can be compared to the next. The caller must ensure that this cell
+** is initialized to NULL and has the "clear" flag set.
+**
+** WHERE_DISTINCT_UNIQUE:
+** In this case it has already been determined that the rows are distinct.
+** No special action is required. The return value is always zero.
+**
+** Parameter pEList is the list of expressions used to generated the
+** contents of each row. It is used by this routine to determine (a)
+** how many elements there are in the array of registers and (b) the
+** collation sequences that should be used for the comparisons if
+** eTnctType is WHERE_DISTINCT_ORDERED.
*/
-static void codeDistinct(
+static int codeDistinct(
Parse *pParse, /* Parsing and code generating context */
+ int eTnctType, /* WHERE_DISTINCT_* value */
int iTab, /* A sorting index used to test for distinctness */
int addrRepeat, /* Jump to here if not distinct */
- int N, /* Number of elements */
- int iMem /* First element */
+ ExprList *pEList, /* Expression for each element */
+ int regElem /* First element */
){
- Vdbe *v;
- int r1;
+ int iRet = 0;
+ int nResultCol = pEList->nExpr;
+ Vdbe *v = pParse->pVdbe;
- v = pParse->pVdbe;
- r1 = sqlite3GetTempReg(pParse);
- sqlite3VdbeAddOp4Int(v, OP_Found, iTab, addrRepeat, iMem, N); VdbeCoverage(v);
- sqlite3VdbeAddOp3(v, OP_MakeRecord, iMem, N, r1);
- sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iTab, r1, iMem, N);
- sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
- sqlite3ReleaseTempReg(pParse, r1);
+ switch( eTnctType ){
+ case WHERE_DISTINCT_ORDERED: {
+ int i;
+ int iJump; /* Jump destination */
+ int regPrev; /* Previous row content */
+
+ /* Allocate space for the previous row */
+ iRet = regPrev = pParse->nMem+1;
+ pParse->nMem += nResultCol;
+
+ iJump = sqlite3VdbeCurrentAddr(v) + nResultCol;
+ for(i=0; i<nResultCol; i++){
+ CollSeq *pColl = sqlite3ExprCollSeq(pParse, pEList->a[i].pExpr);
+ if( i<nResultCol-1 ){
+ sqlite3VdbeAddOp3(v, OP_Ne, regElem+i, iJump, regPrev+i);
+ VdbeCoverage(v);
+ }else{
+ sqlite3VdbeAddOp3(v, OP_Eq, regElem+i, addrRepeat, regPrev+i);
+ VdbeCoverage(v);
+ }
+ sqlite3VdbeChangeP4(v, -1, (const char *)pColl, P4_COLLSEQ);
+ sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
+ }
+ assert( sqlite3VdbeCurrentAddr(v)==iJump || pParse->db->mallocFailed );
+ sqlite3VdbeAddOp3(v, OP_Copy, regElem, regPrev, nResultCol-1);
+ break;
+ }
+
+ case WHERE_DISTINCT_UNIQUE: {
+ /* nothing to do */
+ break;
+ }
+
+ default: {
+ int r1 = sqlite3GetTempReg(pParse);
+ sqlite3VdbeAddOp4Int(v, OP_Found, iTab, addrRepeat, regElem, nResultCol);
+ VdbeCoverage(v);
+ sqlite3VdbeAddOp3(v, OP_MakeRecord, regElem, nResultCol, r1);
+ sqlite3VdbeAddOp4Int(v, OP_IdxInsert, iTab, r1, regElem, nResultCol);
+ sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
+ sqlite3ReleaseTempReg(pParse, r1);
+ iRet = iTab;
+ break;
+ }
+ }
+
+ return iRet;
+}
+
+/*
+** A call to this function must be made for each call to codeDistinct().
+** Parameter is passed the value returned by that call to codeDistinct(),
+** and iOpenEphAddr the address of the instruction used to open the
+** ephemeral table (that may be) used by codeDistinct().
+**
+** Argument eTnctType is passed the strategy to be used for any DISTINCT
+** operation, as returned by sqlite3WhereIsDistinct(). If the strategy
+** is WHERE_DISTINCT_NOOP or WHERE_DISTINCT_UNORDERED, this function is
+** a no-op. Otherwise:
+**
+** WHERE_DISTINCT_UNIQUE:
+** In this case the ephemeral table is not required. So instruction
+** iOpenEphAddr is replaced by an OP_Noop.
+**
+** WHERE_DISTINCT_ORDERED:
+** In this case the ephemeral table is not required. The instruction
+** iOpenEphAddr is replaced by an OP_Null instruction to set register
+** iVal to a NULL value with the "clear" flag set (see comments above
+** codeDistinct() for details).
+*/
+static void fixDistinctOpenEph(
+ Parse *pParse, /* Parsing and code generating context */
+ int eTnctType, /* WHERE_DISTINCT_* value */
+ int iVal, /* Value returned by codeDistinct() */
+ int iOpenEphAddr /* Address of OP_OpenEphemeral instruction for iTab */
+){
+ if( eTnctType==WHERE_DISTINCT_UNIQUE || eTnctType==WHERE_DISTINCT_ORDERED ){
+ Vdbe *v = pParse->pVdbe;
+ sqlite3VdbeChangeToNoop(v, iOpenEphAddr);
+ if( eTnctType==WHERE_DISTINCT_ORDERED ){
+ /* Change the OP_OpenEphemeral to an OP_Null that sets the MEM_Cleared
+ ** bit on the first register of the previous value. This will cause the
+ ** OP_Ne added in codeDistinct() to always fail on the first iteration of
+ ** the loop even if the first row is all NULLs. */
+ VdbeOp *pOp = sqlite3VdbeGetOp(v, iOpenEphAddr);
+ pOp->opcode = OP_Null;
+ pOp->p1 = 1;
+ pOp->p2 = iVal;
+ }
+ }
}
#ifdef SQLITE_ENABLE_SORTER_REFERENCES
@@ -1013,59 +1128,11 @@ static void selectInnerLoop(
** part of the result.
*/
if( hasDistinct ){
- switch( pDistinct->eTnctType ){
- case WHERE_DISTINCT_ORDERED: {
- VdbeOp *pOp; /* No longer required OpenEphemeral instr. */
- int iJump; /* Jump destination */
- int regPrev; /* Previous row content */
-
- /* Allocate space for the previous row */
- regPrev = pParse->nMem+1;
- pParse->nMem += nResultCol;
-
- /* Change the OP_OpenEphemeral coded earlier to an OP_Null
- ** sets the MEM_Cleared bit on the first register of the
- ** previous value. This will cause the OP_Ne below to always
- ** fail on the first iteration of the loop even if the first
- ** row is all NULLs.
- */
- sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct);
- pOp = sqlite3VdbeGetOp(v, pDistinct->addrTnct);
- pOp->opcode = OP_Null;
- pOp->p1 = 1;
- pOp->p2 = regPrev;
- pOp = 0; /* Ensure pOp is not used after sqlite3VdbeAddOp() */
-
- iJump = sqlite3VdbeCurrentAddr(v) + nResultCol;
- for(i=0; i<nResultCol; i++){
- CollSeq *pColl = sqlite3ExprCollSeq(pParse, p->pEList->a[i].pExpr);
- if( i<nResultCol-1 ){
- sqlite3VdbeAddOp3(v, OP_Ne, regResult+i, iJump, regPrev+i);
- VdbeCoverage(v);
- }else{
- sqlite3VdbeAddOp3(v, OP_Eq, regResult+i, iContinue, regPrev+i);
- VdbeCoverage(v);
- }
- sqlite3VdbeChangeP4(v, -1, (const char *)pColl, P4_COLLSEQ);
- sqlite3VdbeChangeP5(v, SQLITE_NULLEQ);
- }
- assert( sqlite3VdbeCurrentAddr(v)==iJump || pParse->db->mallocFailed );
- sqlite3VdbeAddOp3(v, OP_Copy, regResult, regPrev, nResultCol-1);
- break;
- }
-
- case WHERE_DISTINCT_UNIQUE: {
- sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct);
- break;
- }
-
- default: {
- assert( pDistinct->eTnctType==WHERE_DISTINCT_UNORDERED );
- codeDistinct(pParse, pDistinct->tabTnct, iContinue, nResultCol,
- regResult);
- break;
- }
- }
+ int eType = pDistinct->eTnctType;
+ int iTab = pDistinct->tabTnct;
+ assert( nResultCol==p->pEList->nExpr );
+ iTab = codeDistinct(pParse, eType, iTab, iContinue, p->pEList, regResult);
+ fixDistinctOpenEph(pParse, eType, iTab, pDistinct->addrTnct);
if( pSort==0 ){
codeOffset(v, p->iOffset, iContinue);
}
@@ -5645,8 +5712,8 @@ static void resetAccumulator(Parse *pParse, AggInfo *pAggInfo){
pFunc->iDistinct = -1;
}else{
KeyInfo *pKeyInfo = sqlite3KeyInfoFromExprList(pParse, pE->x.pList,0,0);
- sqlite3VdbeAddOp4(v, OP_OpenEphemeral, pFunc->iDistinct, 0, 0,
- (char*)pKeyInfo, P4_KEYINFO);
+ pFunc->iDistAddr = sqlite3VdbeAddOp4(v, OP_OpenEphemeral,
+ pFunc->iDistinct, 0, 0, (char*)pKeyInfo, P4_KEYINFO);
}
}
}
@@ -5678,7 +5745,12 @@ static void finalizeAggFunctions(Parse *pParse, AggInfo *pAggInfo){
** registers if register regAcc contains 0. The caller will take care
** of setting and clearing regAcc.
*/
-static void updateAccumulator(Parse *pParse, int regAcc, AggInfo *pAggInfo){
+static void updateAccumulator(
+ Parse *pParse,
+ int regAcc,
+ AggInfo *pAggInfo,
+ int eDistinctType
+){
Vdbe *v = pParse->pVdbe;
int i;
int regHit = 0;
@@ -5724,13 +5796,14 @@ static void updateAccumulator(Parse *pParse, int regAcc, AggInfo *pAggInfo){
nArg = 0;
regAgg = 0;
}
- if( pF->iDistinct>=0 ){
+ if( pF->iDistinct>=0 && pList ){
if( addrNext==0 ){
addrNext = sqlite3VdbeMakeLabel(pParse);
}
testcase( nArg==0 ); /* Error condition */
testcase( nArg>1 ); /* Also an error */
- codeDistinct(pParse, pF->iDistinct, addrNext, 1, regAgg);
+ pF->iDistinct = codeDistinct(pParse, eDistinctType,
+ pF->iDistinct, addrNext, pList, regAgg);
}
if( pF->pFunc->funcFlags & SQLITE_FUNC_NEEDCOLL ){
CollSeq *pColl = 0;
@@ -6762,6 +6835,20 @@ int sqlite3Select(
int addrSortingIdx; /* The OP_OpenEphemeral for the sorting index */
int addrReset; /* Subroutine for resetting the accumulator */
int regReset; /* Return address register for reset subroutine */
+ ExprList *pDistinct = 0;
+ u16 distFlag = 0;
+ int eDist = WHERE_DISTINCT_NOOP;
+
+ if( pAggInfo->nFunc==1
+ && pAggInfo->aFunc[0].iDistinct>=0
+ && pAggInfo->aFunc[0].pFExpr->x.pList
+ ){
+ Expr *pExpr = pAggInfo->aFunc[0].pFExpr->x.pList->a[0].pExpr;
+ pExpr = sqlite3ExprDup(db, pExpr, 0);
+ pDistinct = sqlite3ExprListDup(db, pGroupBy, 0);
+ pDistinct = sqlite3ExprListAppend(pParse, pDistinct, pExpr);
+ distFlag = pDistinct ? WHERE_WANT_DISTINCT : 0;
+ }
/* If there is a GROUP BY clause we might need a sorting index to
** implement it. Allocate that sorting index now. If it turns out
@@ -6798,10 +6885,12 @@ int sqlite3Select(
*/
sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
SELECTTRACE(1,pParse,p,("WhereBegin\n"));
- pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pGroupBy, 0,
- WHERE_GROUPBY | (orderByGrp ? WHERE_SORTBYGROUP : 0), 0
+ pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pGroupBy, pDistinct,
+ WHERE_GROUPBY | (orderByGrp ? WHERE_SORTBYGROUP : 0) | distFlag, 0
);
+ sqlite3ExprListDelete(db, pDistinct);
if( pWInfo==0 ) goto select_end;
+ eDist = sqlite3WhereIsDistinct(pWInfo);
SELECTTRACE(1,pParse,p,("WhereBegin returns\n"));
if( sqlite3WhereIsOrdered(pWInfo)==pGroupBy->nExpr ){
/* The optimizer is able to deliver rows in group by order so
@@ -6919,7 +7008,7 @@ int sqlite3Select(
** the current row
*/
sqlite3VdbeJumpHere(v, addr1);
- updateAccumulator(pParse, iUseFlag, pAggInfo);
+ updateAccumulator(pParse, iUseFlag, pAggInfo, eDist);
sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag);
VdbeComment((v, "indicate data in accumulator"));
@@ -6975,7 +7064,11 @@ int sqlite3Select(
sqlite3VdbeAddOp2(v, OP_Integer, 0, iUseFlag);
VdbeComment((v, "indicate accumulator empty"));
sqlite3VdbeAddOp1(v, OP_Return, regReset);
-
+
+ if( eDist!=WHERE_DISTINCT_NOOP ){
+ struct AggInfo_func *pF = &pAggInfo->aFunc[0];
+ fixDistinctOpenEph(pParse, eDist, pF->iDistinct, pF->iDistAddr);
+ }
} /* endif pGroupBy. Begin aggregate queries without GROUP BY: */
else {
Table *pTab;
@@ -7039,6 +7132,9 @@ int sqlite3Select(
explainSimpleCount(pParse, pTab, pBest);
}else{
int regAcc = 0; /* "populate accumulators" flag */
+ ExprList *pDistinct = 0;
+ u16 distFlag = 0;
+ int eDist;
/* If there are accumulator registers but no min() or max() functions
** without FILTER clauses, allocate register regAcc. Register regAcc
@@ -7062,6 +7158,9 @@ int sqlite3Select(
regAcc = ++pParse->nMem;
sqlite3VdbeAddOp2(v, OP_Integer, 0, regAcc);
}
+ }else if( pAggInfo->nFunc==1 && pAggInfo->aFunc[0].iDistinct>=0 ){
+ pDistinct = pAggInfo->aFunc[0].pFExpr->x.pList;
+ distFlag = pDistinct ? WHERE_WANT_DISTINCT : 0;
}
/* This case runs if the aggregate has no GROUP BY clause. The
@@ -7081,12 +7180,18 @@ int sqlite3Select(
SELECTTRACE(1,pParse,p,("WhereBegin\n"));
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pMinMaxOrderBy,
- 0, minMaxFlag, 0);
+ pDistinct, minMaxFlag|distFlag, 0);
if( pWInfo==0 ){
goto select_end;
}
SELECTTRACE(1,pParse,p,("WhereBegin returns\n"));
- updateAccumulator(pParse, regAcc, pAggInfo);
+ eDist = sqlite3WhereIsDistinct(pWInfo);
+ updateAccumulator(pParse, regAcc, pAggInfo, eDist);
+ if( eDist!=WHERE_DISTINCT_NOOP ){
+ struct AggInfo_func *pF = &pAggInfo->aFunc[0];
+ fixDistinctOpenEph(pParse, eDist, pF->iDistinct, pF->iDistAddr);
+ }
+
if( regAcc ) sqlite3VdbeAddOp2(v, OP_Integer, 1, regAcc);
if( minMaxFlag ){
sqlite3WhereMinMaxOptEarlyOut(v, pWInfo);
generated by cgit v1.2.3 (git 2.25.1) at 2025-07-21 04:53:17 +0000