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Overview
| Comment: | Multiply all cursor step cost estimates by the estimated size of the row in bytes, in order to get the query planner ot make use of estimated row sizes. This check-in uses magic numbers in a few places (for example, estimates of the size of output rows) and needs lots of refinement. Consider this a proof-of-concept only. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | row-size-est |
| Files: | files | file ages | folders |
| SHA1: |
cb34cfe57c2a664fbfae8106e9511440 |
| User & Date: | drh 2013-10-07 17:32:15 |
Context
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2013-10-08
| ||
| 18:40 | Further refinement of the idea of multiplying run-time cost estimates by the estimated row size. check-in: 18bd6ba9 user: drh tags: row-size-est | |
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2013-10-07
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| 17:32 | Multiply all cursor step cost estimates by the estimated size of the row in bytes, in order to get the query planner ot make use of estimated row sizes. This check-in uses magic numbers in a few places (for example, estimates of the size of output rows) and needs lots of refinement. Consider this a proof-of-concept only. check-in: cb34cfe5 user: drh tags: row-size-est | |
| 10:48 | Merge bug fixes from trunk. check-in: 1d7b2dc0 user: drh tags: row-size-est | |
Changes
Changes to src/where.c.
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#endif
if( (pNew->wsFlags & (WHERE_IDX_ONLY|WHERE_IPK))==0 ){
/* Each row involves a step of the index, then a binary search of
** the main table */
pNew->rRun = sqlite3LogEstAdd(pNew->rRun,rLogSize>27 ? rLogSize-17 : 10);
}
/* Step cost for each output row */
pNew->rRun = sqlite3LogEstAdd(pNew->rRun, pNew->nOut);
whereLoopOutputAdjust(pBuilder->pWC, pNew, pSrc->iCursor);
rc = whereLoopInsert(pBuilder, pNew);
if( (pNew->wsFlags & WHERE_TOP_LIMIT)==0
&& pNew->u.btree.nEq<(pProbe->nColumn + (pProbe->zName!=0))
){
whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nInMul+nIn);
}
................................................................................
WhereLoop *pNew; /* Template WhereLoop object */
int rc = SQLITE_OK; /* Return code */
int iSortIdx = 1; /* Index number */
int b; /* A boolean value */
LogEst rSize; /* number of rows in the table */
LogEst rLogSize; /* Logarithm of the number of rows in the table */
WhereClause *pWC; /* The parsed WHERE clause */
pNew = pBuilder->pNew;
pWInfo = pBuilder->pWInfo;
pTabList = pWInfo->pTabList;
pSrc = pTabList->a + pNew->iTab;
pWC = pBuilder->pWC;
assert( !IsVirtual(pSrc->pTab) );
if( pSrc->pIndex ){
/* An INDEXED BY clause specifies a particular index to use */
pProbe = pSrc->pIndex;
}else{
................................................................................
** indices to follow */
Index *pFirst; /* First of real indices on the table */
memset(&sPk, 0, sizeof(Index));
sPk.nColumn = 1;
sPk.aiColumn = &aiColumnPk;
sPk.aiRowEst = aiRowEstPk;
sPk.onError = OE_Replace;
sPk.pTable = pSrc->pTab;
aiRowEstPk[0] = pSrc->pTab->nRowEst;
aiRowEstPk[1] = 1;
pFirst = pSrc->pTab->pIndex;
if( pSrc->notIndexed==0 ){
/* The real indices of the table are only considered if the
** NOT INDEXED qualifier is omitted from the FROM clause */
sPk.pNext = pFirst;
}
pProbe = &sPk;
}
rSize = sqlite3LogEst(pSrc->pTab->nRowEst);
rLogSize = estLog(rSize);
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
/* Automatic indexes */
if( !pBuilder->pOrSet
&& (pWInfo->pParse->db->flags & SQLITE_AutoIndex)!=0
&& pSrc->pIndex==0
................................................................................
pNew->u.btree.pIndex = 0;
pNew->nLTerm = 1;
pNew->aLTerm[0] = pTerm;
/* TUNING: One-time cost for computing the automatic index is
** approximately 7*N*log2(N) where N is the number of rows in
** the table being indexed. */
pNew->rSetup = rLogSize + rSize + 28; assert( 28==sqlite3LogEst(7) );
/* TUNING: Each index lookup yields 20 rows in the table. This
** is more than the usual guess of 10 rows, since we have no way
** of knowning how selective the index will ultimately be. It would
** not be unreasonable to make this value much larger. */
pNew->nOut = 43; assert( 43==sqlite3LogEst(20) );
pNew->rRun = sqlite3LogEstAdd(rLogSize,pNew->nOut);
pNew->wsFlags = WHERE_AUTO_INDEX;
pNew->prereq = mExtra | pTerm->prereqRight;
rc = whereLoopInsert(pBuilder, pNew);
}
}
}
#endif /* SQLITE_OMIT_AUTOMATIC_INDEX */
................................................................................
pNew->wsFlags = WHERE_IPK;
/* Full table scan */
pNew->iSortIdx = b ? iSortIdx : 0;
/* TUNING: Cost of full table scan is 3*(N + log2(N)).
** + The extra 3 factor is to encourage the use of indexed lookups
** over full scans. FIXME */
pNew->rRun = sqlite3LogEstAdd(rSize,rLogSize) + 16;
whereLoopOutputAdjust(pWC, pNew, pSrc->iCursor);
rc = whereLoopInsert(pBuilder, pNew);
pNew->nOut = rSize;
if( rc ) break;
}else{
Bitmask m = pSrc->colUsed & ~columnsInIndex(pProbe);
pNew->wsFlags = (m==0) ? (WHERE_IDX_ONLY|WHERE_INDEXED) : WHERE_INDEXED;
................................................................................
pNew->rRun = sqlite3LogEstAdd(rSize,rLogSize) + 10;
}else{
assert( b!=0 );
/* TUNING: Cost of scanning a non-covering index is (N+1)*log2(N)
** which we will simplify to just N*log2(N) */
pNew->rRun = rSize + rLogSize;
}
whereLoopOutputAdjust(pWC, pNew, pSrc->iCursor);
rc = whereLoopInsert(pBuilder, pNew);
pNew->nOut = rSize;
if( rc ) break;
}
}
................................................................................
pNew->u.vtab.idxNum = pIdxInfo->idxNum;
pNew->u.vtab.needFree = pIdxInfo->needToFreeIdxStr;
pIdxInfo->needToFreeIdxStr = 0;
pNew->u.vtab.idxStr = pIdxInfo->idxStr;
pNew->u.vtab.isOrdered = (u8)((pIdxInfo->nOrderBy!=0)
&& pIdxInfo->orderByConsumed);
pNew->rSetup = 0;
pNew->rRun = sqlite3LogEstFromDouble(pIdxInfo->estimatedCost);
/* TUNING: Every virtual table query returns 25 rows */
pNew->nOut = 46; assert( 46==sqlite3LogEst(25) );
whereLoopInsert(pBuilder, pNew);
if( pNew->u.vtab.needFree ){
sqlite3_free(pNew->u.vtab.idxStr);
pNew->u.vtab.needFree = 0;
}
................................................................................
** to sqlite3WhereBegin() was concerned about sorting */
rSortCost = 0;
if( pWInfo->pOrderBy==0 || nRowEst==0 ){
aFrom[0].isOrderedValid = 1;
}else{
/* TUNING: Estimated cost of sorting is N*log2(N) where N is the
** number of output rows. */
rSortCost = nRowEst + estLog(nRowEst);
WHERETRACE(0x002,("---- sort cost=%-3d\n", rSortCost));
}
/* Compute successively longer WherePaths using the previous generation
** of WherePaths as the basis for the next. Keep track of the mxChoice
** best paths at each generation */
for(iLoop=0; iLoop<nLoop; iLoop++){
|
| > > | | | > | | > | | |
4364 4365 4366 4367 4368 4369 4370 4371 4372 4373 4374 4375 4376 4377 4378 .... 4467 4468 4469 4470 4471 4472 4473 4474 4475 4476 4477 4478 4479 4480 4481 4482 4483 4484 4485 4486 4487 .... 4491 4492 4493 4494 4495 4496 4497 4498 4499 4500 4501 4502 4503 4504 4505 4506 4507 4508 4509 4510 4511 4512 4513 4514 4515 4516 .... 4528 4529 4530 4531 4532 4533 4534 4535 4536 4537 4538 4539 4540 4541 4542 4543 4544 4545 4546 4547 4548 .... 4569 4570 4571 4572 4573 4574 4575 4576 4577 4578 4579 4580 4581 4582 4583 .... 4601 4602 4603 4604 4605 4606 4607 4608 4609 4610 4611 4612 4613 4614 4615 .... 4773 4774 4775 4776 4777 4778 4779 4780 4781 4782 4783 4784 4785 4786 4787 .... 5264 5265 5266 5267 5268 5269 5270 5271 5272 5273 5274 5275 5276 5277 5278 |
#endif
if( (pNew->wsFlags & (WHERE_IDX_ONLY|WHERE_IPK))==0 ){
/* Each row involves a step of the index, then a binary search of
** the main table */
pNew->rRun = sqlite3LogEstAdd(pNew->rRun,rLogSize>27 ? rLogSize-17 : 10);
}
/* Step cost for each output row */
pNew->rRun = sqlite3LogEstAdd(pNew->rRun, pNew->nOut) + pProbe->szIdxRow;
whereLoopOutputAdjust(pBuilder->pWC, pNew, pSrc->iCursor);
rc = whereLoopInsert(pBuilder, pNew);
if( (pNew->wsFlags & WHERE_TOP_LIMIT)==0
&& pNew->u.btree.nEq<(pProbe->nColumn + (pProbe->zName!=0))
){
whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nInMul+nIn);
}
................................................................................
WhereLoop *pNew; /* Template WhereLoop object */
int rc = SQLITE_OK; /* Return code */
int iSortIdx = 1; /* Index number */
int b; /* A boolean value */
LogEst rSize; /* number of rows in the table */
LogEst rLogSize; /* Logarithm of the number of rows in the table */
WhereClause *pWC; /* The parsed WHERE clause */
Table *pTab; /* Table being queried */
pNew = pBuilder->pNew;
pWInfo = pBuilder->pWInfo;
pTabList = pWInfo->pTabList;
pSrc = pTabList->a + pNew->iTab;
pTab = pSrc->pTab;
pWC = pBuilder->pWC;
assert( !IsVirtual(pSrc->pTab) );
if( pSrc->pIndex ){
/* An INDEXED BY clause specifies a particular index to use */
pProbe = pSrc->pIndex;
}else{
................................................................................
** indices to follow */
Index *pFirst; /* First of real indices on the table */
memset(&sPk, 0, sizeof(Index));
sPk.nColumn = 1;
sPk.aiColumn = &aiColumnPk;
sPk.aiRowEst = aiRowEstPk;
sPk.onError = OE_Replace;
sPk.pTable = pTab;
aiRowEstPk[0] = pTab->nRowEst;
aiRowEstPk[1] = 1;
pFirst = pSrc->pTab->pIndex;
if( pSrc->notIndexed==0 ){
/* The real indices of the table are only considered if the
** NOT INDEXED qualifier is omitted from the FROM clause */
sPk.pNext = pFirst;
}
pProbe = &sPk;
}
rSize = sqlite3LogEst(pTab->nRowEst);
rLogSize = estLog(rSize);
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
/* Automatic indexes */
if( !pBuilder->pOrSet
&& (pWInfo->pParse->db->flags & SQLITE_AutoIndex)!=0
&& pSrc->pIndex==0
................................................................................
pNew->u.btree.pIndex = 0;
pNew->nLTerm = 1;
pNew->aLTerm[0] = pTerm;
/* TUNING: One-time cost for computing the automatic index is
** approximately 7*N*log2(N) where N is the number of rows in
** the table being indexed. */
pNew->rSetup = rLogSize + rSize + 28; assert( 28==sqlite3LogEst(7) );
pNew->rSetup += pTab->szTabRow;
/* TUNING: Each index lookup yields 20 rows in the table. This
** is more than the usual guess of 10 rows, since we have no way
** of knowning how selective the index will ultimately be. It would
** not be unreasonable to make this value much larger. */
pNew->nOut = 43; assert( 43==sqlite3LogEst(20) );
pNew->rRun = sqlite3LogEstAdd(rLogSize,pNew->nOut) + pTab->szTabRow;
pNew->wsFlags = WHERE_AUTO_INDEX;
pNew->prereq = mExtra | pTerm->prereqRight;
rc = whereLoopInsert(pBuilder, pNew);
}
}
}
#endif /* SQLITE_OMIT_AUTOMATIC_INDEX */
................................................................................
pNew->wsFlags = WHERE_IPK;
/* Full table scan */
pNew->iSortIdx = b ? iSortIdx : 0;
/* TUNING: Cost of full table scan is 3*(N + log2(N)).
** + The extra 3 factor is to encourage the use of indexed lookups
** over full scans. FIXME */
pNew->rRun = sqlite3LogEstAdd(rSize,rLogSize) + 16 + pTab->szTabRow;
whereLoopOutputAdjust(pWC, pNew, pSrc->iCursor);
rc = whereLoopInsert(pBuilder, pNew);
pNew->nOut = rSize;
if( rc ) break;
}else{
Bitmask m = pSrc->colUsed & ~columnsInIndex(pProbe);
pNew->wsFlags = (m==0) ? (WHERE_IDX_ONLY|WHERE_INDEXED) : WHERE_INDEXED;
................................................................................
pNew->rRun = sqlite3LogEstAdd(rSize,rLogSize) + 10;
}else{
assert( b!=0 );
/* TUNING: Cost of scanning a non-covering index is (N+1)*log2(N)
** which we will simplify to just N*log2(N) */
pNew->rRun = rSize + rLogSize;
}
pNew->rRun += pProbe->szIdxRow;
whereLoopOutputAdjust(pWC, pNew, pSrc->iCursor);
rc = whereLoopInsert(pBuilder, pNew);
pNew->nOut = rSize;
if( rc ) break;
}
}
................................................................................
pNew->u.vtab.idxNum = pIdxInfo->idxNum;
pNew->u.vtab.needFree = pIdxInfo->needToFreeIdxStr;
pIdxInfo->needToFreeIdxStr = 0;
pNew->u.vtab.idxStr = pIdxInfo->idxStr;
pNew->u.vtab.isOrdered = (u8)((pIdxInfo->nOrderBy!=0)
&& pIdxInfo->orderByConsumed);
pNew->rSetup = 0;
pNew->rRun = sqlite3LogEstFromDouble(pIdxInfo->estimatedCost) + 55;
/* TUNING: Every virtual table query returns 25 rows */
pNew->nOut = 46; assert( 46==sqlite3LogEst(25) );
whereLoopInsert(pBuilder, pNew);
if( pNew->u.vtab.needFree ){
sqlite3_free(pNew->u.vtab.idxStr);
pNew->u.vtab.needFree = 0;
}
................................................................................
** to sqlite3WhereBegin() was concerned about sorting */
rSortCost = 0;
if( pWInfo->pOrderBy==0 || nRowEst==0 ){
aFrom[0].isOrderedValid = 1;
}else{
/* TUNING: Estimated cost of sorting is N*log2(N) where N is the
** number of output rows. */
rSortCost = nRowEst + estLog(nRowEst) + 55;
WHERETRACE(0x002,("---- sort cost=%-3d\n", rSortCost));
}
/* Compute successively longer WherePaths using the previous generation
** of WherePaths as the basis for the next. Keep track of the mxChoice
** best paths at each generation */
for(iLoop=0; iLoop<nLoop; iLoop++){
|