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Overview
Comment: | Adjust the query planner to keep track of the number of ORDER BY terms satisfied. Still doesn't do anything with this information. Some tests fail after this check-in, but all failures are believed to be benign. The failures will be addressed at a later stage. |
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Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | orderby-planning |
Files: | files | file ages | folders |
SHA1: |
59d49b7fc49fa290e04a02653e7268c8 |
User & Date: | drh 2014-03-18 18:59:07.798 |
Context
2014-03-18
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20:33 | Make the partial-ORDER-BY information in the query planner available to the SELECT code generator. Still doesn't make a difference in the generated code. (check-in: e258df236b user: drh tags: orderby-planning) | |
18:59 | Adjust the query planner to keep track of the number of ORDER BY terms satisfied. Still doesn't do anything with this information. Some tests fail after this check-in, but all failures are believed to be benign. The failures will be addressed at a later stage. (check-in: 59d49b7fc4 user: drh tags: orderby-planning) | |
15:30 | Experiments with the optimization of ORDER BY and GROUP BY clauses. (check-in: b150902579 user: drh tags: orderby-planning) | |
Changes
Changes to src/where.c.
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4912 4913 4914 4915 4916 4917 4918 | if( (mTerm&~orderDistinctMask)==0 ){ obSat |= MASKBIT(i); } } } } /* End the loop over all WhereLoops from outer-most down to inner-most */ if( obSat==obDone ) return nOrderBy; | | > > > > > > | 4912 4913 4914 4915 4916 4917 4918 4919 4920 4921 4922 4923 4924 4925 4926 4927 4928 4929 4930 4931 4932 | if( (mTerm&~orderDistinctMask)==0 ){ obSat |= MASKBIT(i); } } } } /* End the loop over all WhereLoops from outer-most down to inner-most */ if( obSat==obDone ) return nOrderBy; if( !isOrderDistinct ){ for(i=nOrderBy-1; i>0; i--){ Bitmask m = MASKBIT(i) - 1; if( (obSat&m)==m ) return i; } return 0; } return -1; } #ifdef WHERETRACE_ENABLED /* For debugging use only: */ static const char *wherePathName(WherePath *pPath, int nLoop, WhereLoop *pLast){ static char zName[65]; |
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4949 4950 4951 4952 4953 4954 4955 4956 4957 4958 4959 | int mxChoice; /* Maximum number of simultaneous paths tracked */ int nLoop; /* Number of terms in the join */ Parse *pParse; /* Parsing context */ sqlite3 *db; /* The database connection */ int iLoop; /* Loop counter over the terms of the join */ int ii, jj; /* Loop counters */ int mxI = 0; /* Index of next entry to replace */ LogEst rCost; /* Cost of a path */ LogEst nOut; /* Number of outputs */ LogEst mxCost = 0; /* Maximum cost of a set of paths */ LogEst mxOut = 0; /* Maximum nOut value on the set of paths */ | > < | 4955 4956 4957 4958 4959 4960 4961 4962 4963 4964 4965 4966 4967 4968 4969 4970 4971 4972 4973 | int mxChoice; /* Maximum number of simultaneous paths tracked */ int nLoop; /* Number of terms in the join */ Parse *pParse; /* Parsing context */ sqlite3 *db; /* The database connection */ int iLoop; /* Loop counter over the terms of the join */ int ii, jj; /* Loop counters */ int mxI = 0; /* Index of next entry to replace */ int nOrderBy; /* Number of ORDER BY clause terms */ LogEst rCost; /* Cost of a path */ LogEst nOut; /* Number of outputs */ LogEst mxCost = 0; /* Maximum cost of a set of paths */ LogEst mxOut = 0; /* Maximum nOut value on the set of paths */ int nTo, nFrom; /* Number of valid entries in aTo[] and aFrom[] */ WherePath *aFrom; /* All nFrom paths at the previous level */ WherePath *aTo; /* The nTo best paths at the current level */ WherePath *pFrom; /* An element of aFrom[] that we are working on */ WherePath *pTo; /* An element of aTo[] that we are working on */ WhereLoop *pWLoop; /* One of the WhereLoop objects */ WhereLoop **pX; /* Used to divy up the pSpace memory */ |
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4995 4996 4997 4998 4999 5000 5001 | ** of computing an automatic index is not paid back within the first 25 ** rows, then do not use the automatic index. */ aFrom[0].nRow = MIN(pParse->nQueryLoop, 46); assert( 46==sqlite3LogEst(25) ); nFrom = 1; /* Precompute the cost of sorting the final result set, if the caller ** to sqlite3WhereBegin() was concerned about sorting */ | < > < < < < < < > | 5001 5002 5003 5004 5005 5006 5007 5008 5009 5010 5011 5012 5013 5014 5015 5016 5017 5018 5019 5020 | ** of computing an automatic index is not paid back within the first 25 ** rows, then do not use the automatic index. */ aFrom[0].nRow = MIN(pParse->nQueryLoop, 46); assert( 46==sqlite3LogEst(25) ); nFrom = 1; /* Precompute the cost of sorting the final result set, if the caller ** to sqlite3WhereBegin() was concerned about sorting */ if( pWInfo->pOrderBy==0 || nRowEst==0 ){ aFrom[0].isOrdered = 0; nOrderBy = 0; }else{ aFrom[0].isOrdered = -1; nOrderBy = pWInfo->pOrderBy->nExpr; } /* 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++){ nTo = 0; |
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5030 5031 5032 5033 5034 5035 5036 | rCost = sqlite3LogEstAdd(rCost, pFrom->rCost); nOut = pFrom->nRow + pWLoop->nOut; maskNew = pFrom->maskLoop | pWLoop->maskSelf; if( isOrdered<0 ){ isOrdered = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy, pFrom, pWInfo->wctrlFlags, iLoop, pWLoop, &revMask); | | > > > > > > > > > | 5031 5032 5033 5034 5035 5036 5037 5038 5039 5040 5041 5042 5043 5044 5045 5046 5047 5048 5049 5050 5051 5052 5053 5054 | rCost = sqlite3LogEstAdd(rCost, pFrom->rCost); nOut = pFrom->nRow + pWLoop->nOut; maskNew = pFrom->maskLoop | pWLoop->maskSelf; if( isOrdered<0 ){ isOrdered = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pOrderBy, pFrom, pWInfo->wctrlFlags, iLoop, pWLoop, &revMask); if( isOrdered>=0 && isOrdered<nOrderBy ){ /* TUNING: Estimated cost of sorting cost as roughly 4*N*log(N). ** If some but not all of the columns are in sorted order, then ** scale down the log(N) term. */ LogEst rSortCost = 20 + nRowEst + estLog(nRowEst)*(nOrderBy-isOrdered)/nOrderBy; WHERETRACE(0x002, ("---- sort cost=%-3d (%d/%d) increases cost %3d to %-3d\n", rSortCost, (nOrderBy-isOrdered), nOrderBy, rCost, sqlite3LogEstAdd(rCost,rSortCost))); rCost = sqlite3LogEstAdd(rCost, rSortCost); } }else{ revMask = pFrom->revLoop; } /* Check to see if pWLoop should be added to the mxChoice best so far */ for(jj=0, pTo=aTo; jj<nTo; jj++, pTo++){ |
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