Overview
| Comment: | Progress toward getting DISTINCT to use a seek to advance to the next distinct row, when driven by an appropriate index. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | skip-ahead-distinct |
| Files: | files | file ages | folders |
| SHA1: | 9e14aa14cff7ebf7a5e93ce7377838da129d585f |
| User & Date: | drh 2016-04-15 01:55:49 |
Context
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2016-04-15
| ||
| 13:24 | Fixed crash bugs. Still sometimes gets the wrong answers. check-in: 2afcb2c7 user: drh tags: skip-ahead-distinct | |
| 01:55 | Progress toward getting DISTINCT to use a seek to advance to the next distinct row, when driven by an appropriate index. check-in: 9e14aa14 user: drh tags: skip-ahead-distinct | |
|
2016-04-14
| ||
| 19:29 | Work toward improving analysis and code generation for DISTINCT and aggregate queries. Leaf check-in: 129083bd user: drh tags: better-distinct-agg | |
Changes
Changes to src/select.c.
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/* If the DISTINCT keyword was present on the SELECT statement
** and this row has been seen before, then do not make this row
** 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;
................................................................................
}
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;
}
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/* If the DISTINCT keyword was present on the SELECT statement
** and this row has been seen before, then do not make this row
** part of the result.
*/
if( hasDistinct ){
switch( pDistinct->eTnctType ){
case WHERE_DISTINCT_ORDERED: {
#if 0
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;
................................................................................
}
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;
#endif
}
case WHERE_DISTINCT_UNIQUE: {
sqlite3VdbeChangeToNoop(v, pDistinct->addrTnct);
break;
}
|
Changes to src/shell.c.
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if( str_in_array(zOp, azNext) ){
for(i=p2op; i<iOp; i++) p->aiIndent[i] += 2;
}
if( str_in_array(zOp, azGoto) && p2op<p->nIndent
&& (abYield[p2op] || sqlite3_column_int(pSql, 2))
){
for(i=p2op+1; i<iOp; i++) p->aiIndent[i] += 2;
}
}
p->iIndent = 0;
sqlite3_free(abYield);
sqlite3_reset(pSql);
}
|
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if( str_in_array(zOp, azNext) ){
for(i=p2op; i<iOp; i++) p->aiIndent[i] += 2;
}
if( str_in_array(zOp, azGoto) && p2op<p->nIndent
&& (abYield[p2op] || sqlite3_column_int(pSql, 2))
){
for(i=p2op; i<iOp; i++) p->aiIndent[i] += 2;
}
}
p->iIndent = 0;
sqlite3_free(abYield);
sqlite3_reset(pSql);
}
|
Changes to src/where.c.
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/* Load the lowest cost path into pWInfo */
for(iLoop=0; iLoop<nLoop; iLoop++){
WhereLevel *pLevel = pWInfo->a + iLoop;
pLevel->pWLoop = pWLoop = pFrom->aLoop[iLoop];
pLevel->iFrom = pWLoop->iTab;
pLevel->iTabCur = pWInfo->pTabList->a[pLevel->iFrom].iCursor;
}
if( (pWInfo->wctrlFlags & WHERE_WANT_DISTINCT)!=0
&& (pWInfo->wctrlFlags & WHERE_DISTINCTBY)==0
&& pWInfo->eDistinct==WHERE_DISTINCT_NOOP
&& nRowEst
){
Bitmask notUsed;
int rc = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pDistinctSet, pFrom,
................................................................................
assert( iIndexCur>=0 );
if( op ){
sqlite3VdbeAddOp3(v, op, iIndexCur, pIx->tnum, iDb);
sqlite3VdbeSetP4KeyInfo(pParse, pIx);
if( (pLoop->wsFlags & WHERE_CONSTRAINT)!=0
&& (pLoop->wsFlags & (WHERE_COLUMN_RANGE|WHERE_SKIPSCAN))==0
&& (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)==0
){
sqlite3VdbeChangeP5(v, OPFLAG_SEEKEQ); /* Hint to COMDB2 */
}
VdbeComment((v, "%s", pIx->zName));
#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
{
u64 colUsed = 0;
................................................................................
WhereLoop *pLoop;
SrcList *pTabList = pWInfo->pTabList;
sqlite3 *db = pParse->db;
/* Generate loop termination code.
*/
VdbeModuleComment((v, "End WHERE-core"));
sqlite3ExprCacheClear(pParse);
for(i=pWInfo->nLevel-1; i>=0; i--){
int addr;
pLevel = &pWInfo->a[i];
pLoop = pLevel->pWLoop;
sqlite3VdbeResolveLabel(v, pLevel->addrCont);
if( pLevel->op!=OP_Noop ){
sqlite3VdbeAddOp3(v, pLevel->op, pLevel->p1, pLevel->p2, pLevel->p3);
sqlite3VdbeChangeP5(v, pLevel->p5);
VdbeCoverage(v);
VdbeCoverageIf(v, pLevel->op==OP_Next);
VdbeCoverageIf(v, pLevel->op==OP_Prev);
VdbeCoverageIf(v, pLevel->op==OP_VNext);
}
if( pLoop->wsFlags & WHERE_IN_ABLE && pLevel->u.in.nIn>0 ){
struct InLoop *pIn;
int j;
sqlite3VdbeResolveLabel(v, pLevel->addrNxt);
for(j=pLevel->u.in.nIn, pIn=&pLevel->u.in.aInLoop[j-1]; j>0; j--, pIn--){
sqlite3VdbeJumpHere(v, pIn->addrInTop+1);
|
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/* Load the lowest cost path into pWInfo */
for(iLoop=0; iLoop<nLoop; iLoop++){
WhereLevel *pLevel = pWInfo->a + iLoop;
pLevel->pWLoop = pWLoop = pFrom->aLoop[iLoop];
pLevel->iFrom = pWLoop->iTab;
pLevel->iTabCur = pWInfo->pTabList->a[pLevel->iFrom].iCursor;
}
assert( pWInfo->pDistinctSet || (pWInfo->wctrlFlags&WHERE_WANT_DISTINCT)==0 );
if( (pWInfo->wctrlFlags & WHERE_WANT_DISTINCT)!=0
&& (pWInfo->wctrlFlags & WHERE_DISTINCTBY)==0
&& pWInfo->eDistinct==WHERE_DISTINCT_NOOP
&& nRowEst
){
Bitmask notUsed;
int rc = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pDistinctSet, pFrom,
................................................................................
assert( iIndexCur>=0 );
if( op ){
sqlite3VdbeAddOp3(v, op, iIndexCur, pIx->tnum, iDb);
sqlite3VdbeSetP4KeyInfo(pParse, pIx);
if( (pLoop->wsFlags & WHERE_CONSTRAINT)!=0
&& (pLoop->wsFlags & (WHERE_COLUMN_RANGE|WHERE_SKIPSCAN))==0
&& (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)==0
&& pWInfo->eDistinct!=WHERE_DISTINCT_ORDERED
){
sqlite3VdbeChangeP5(v, OPFLAG_SEEKEQ); /* Hint to COMDB2 */
}
VdbeComment((v, "%s", pIx->zName));
#ifdef SQLITE_ENABLE_COLUMN_USED_MASK
{
u64 colUsed = 0;
................................................................................
WhereLoop *pLoop;
SrcList *pTabList = pWInfo->pTabList;
sqlite3 *db = pParse->db;
/* Generate loop termination code.
*/
VdbeModuleComment((v, "End WHERE-core"));
assert( pWInfo->eDistinct!=WHERE_DISTINCT_ORDERED || pWInfo->pDistinctSet!=0);
sqlite3ExprCacheClear(pParse);
for(i=pWInfo->nLevel-1; i>=0; i--){
int addr;
pLevel = &pWInfo->a[i];
pLoop = pLevel->pWLoop;
sqlite3VdbeResolveLabel(v, pLevel->addrCont);
if( pLevel->op!=OP_Noop ){
if( pWInfo->eDistinct==WHERE_DISTINCT_ORDERED ){
int j, k, op;
int r1 = pParse->nMem+1;
int n = 0;
ExprList *pX = pWInfo->pDistinctSet;
for(j=0; j<pX->nExpr; j++){
Expr *pE = sqlite3ExprSkipCollate(pX->a[j].pExpr);
if( pE->op==TK_COLUMN && pE->iTable==pLevel->iTabCur ) n++;
}
for(j=0; j<n; j++){
sqlite3VdbeAddOp3(v, OP_Column, pLevel->iIdxCur, j, r1+j);
}
pParse->nMem += n;
op = pLevel->op==OP_Prev ? OP_SeekLT : OP_SeekGT;
k = sqlite3VdbeAddOp4Int(v, op, pLevel->iIdxCur, 0, r1, n);
VdbeCoverageIf(v, op==OP_SeekLT);
VdbeCoverageIf(v, op==OP_SeekGT);
sqlite3VdbeAddOp2(v, OP_Goto, 1, pLevel->p2);
sqlite3VdbeJumpHere(v, k);
}else{
sqlite3VdbeAddOp3(v, pLevel->op, pLevel->p1, pLevel->p2, pLevel->p3);
sqlite3VdbeChangeP5(v, pLevel->p5);
VdbeCoverage(v);
VdbeCoverageIf(v, pLevel->op==OP_Next);
VdbeCoverageIf(v, pLevel->op==OP_Prev);
VdbeCoverageIf(v, pLevel->op==OP_VNext);
}
}
if( pLoop->wsFlags & WHERE_IN_ABLE && pLevel->u.in.nIn>0 ){
struct InLoop *pIn;
int j;
sqlite3VdbeResolveLabel(v, pLevel->addrNxt);
for(j=pLevel->u.in.nIn, pIn=&pLevel->u.in.aInLoop[j-1]; j>0; j--, pIn--){
sqlite3VdbeJumpHere(v, pIn->addrInTop+1);
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