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Overview
Comment:Simplification to the logic that prevents automatic indexes from being formed on constant expressions.
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SHA1: 36d67e1dd2b4f4c22d02f3c3b8d372074de5523a
User & Date: drh 2014-06-17 09:52:26.975
Context
2014-06-17
12:33
A different approach to the autoindex problem that deletes query-planner code rather than adding it. (check-in: f270fb6e9e user: drh tags: autoindex-improvements)
09:52
Simplification to the logic that prevents automatic indexes from being formed on constant expressions. (check-in: 36d67e1dd2 user: drh tags: autoindex-improvements)
09:00
Allow an automatic index on a WHERE constraint where the RHS is does not reference another table as long as the RHS is not a constant. (check-in: 58acc2a8b3 user: drh tags: autoindex-improvements)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/where.c.
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   && !pSrc->isRecursive
  ){
    /* Generate auto-index WhereLoops */
    WhereTerm *pTerm;
    WhereTerm *pWCEnd = pWC->a + pWC->nTerm;
    for(pTerm=pWC->a; rc==SQLITE_OK && pTerm<pWCEnd; pTerm++){
      if( pTerm->prereqRight & pNew->maskSelf ) continue;
      if( pTerm->prereqRight==0
       && sqlite3ExprIsConstant(pTerm->pExpr->pRight) ){
        continue;
      }
      if( termCanDriveIndex(pTerm, pSrc, 0) ){
        pNew->u.btree.nEq = 1;
        pNew->u.btree.nSkip = 0;
        pNew->u.btree.pIndex = 0;
        pNew->nLTerm = 1;
        pNew->aLTerm[0] = pTerm;
        /* TUNING: One-time cost for computing the automatic index is








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   && !pSrc->isRecursive
  ){
    /* Generate auto-index WhereLoops */
    WhereTerm *pTerm;
    WhereTerm *pWCEnd = pWC->a + pWC->nTerm;
    for(pTerm=pWC->a; rc==SQLITE_OK && pTerm<pWCEnd; pTerm++){
      if( pTerm->prereqRight & pNew->maskSelf ) continue;

      if( sqlite3ExprIsConstant(pTerm->pExpr->pRight) ) continue;


      if( termCanDriveIndex(pTerm, pSrc, 0) ){
        pNew->u.btree.nEq = 1;
        pNew->u.btree.nSkip = 0;
        pNew->u.btree.pIndex = 0;
        pNew->nLTerm = 1;
        pNew->aLTerm[0] = pTerm;
        /* TUNING: One-time cost for computing the automatic index is
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