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Comment:In cases where stat4 data is available but cannot be used because the rhs of a range constraint is too complex a expression, fall back to using the default estimates for number of rows scanned.
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SHA1:e06dc6f0c35f87c44292c71677111b74f073a5c4
User & Date: dan 2014-08-25 18:29:38
Context
2014-08-25
20:11
Allow CAST expressions and unary "+" operators to be used in the DEFAULT argument of an ALTER TABLE ADD COLUMN and to be understand on the RHS of range constraints interpreted by STAT3/4. This involves a rewrite of the implementation of the CAST operator. check-in: 91d8a8d0 user: drh tags: trunk
18:29
In cases where stat4 data is available but cannot be used because the rhs of a range constraint is too complex a expression, fall back to using the default estimates for number of rows scanned. check-in: e06dc6f0 user: dan tags: trunk
11:33
Remove the pager_lookup() function since it is redundant with sqlite3PagerLookup(). check-in: 54164ce4 user: drh tags: trunk
Changes
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Changes to src/where.c.

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        rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq, &bOk);
        if( rc==SQLITE_OK && bOk ){
          tRowcnt iNew;
          whereKeyStats(pParse, p, pRec, 0, a);
          iNew = a[0] + ((pLower->eOperator & WO_GT) ? a[1] : 0);
          if( iNew>iLower ) iLower = iNew;
          nOut--;

        }
      }

      /* If possible, improve on the iUpper estimate using ($P:$U). */
      if( pUpper ){
        int bOk;                    /* True if value is extracted from pExpr */
        Expr *pExpr = pUpper->pExpr->pRight;
................................................................................
        rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq, &bOk);
        if( rc==SQLITE_OK && bOk ){
          tRowcnt iNew;
          whereKeyStats(pParse, p, pRec, 1, a);
          iNew = a[0] + ((pUpper->eOperator & WO_LE) ? a[1] : 0);
          if( iNew<iUpper ) iUpper = iNew;
          nOut--;

        }
      }

      pBuilder->pRec = pRec;
      if( rc==SQLITE_OK ){
        if( iUpper>iLower ){
          nNew = sqlite3LogEst(iUpper - iLower);
        }else{
          nNew = 10;        assert( 10==sqlite3LogEst(2) );
        }
        if( nNew<nOut ){
          nOut = nNew;
        }
        pLoop->nOut = (LogEst)nOut;
        WHERETRACE(0x10, ("range scan regions: %u..%u  est=%d\n",
                           (u32)iLower, (u32)iUpper, nOut));
        return SQLITE_OK;
      }
    }else{
      int bDone = 0;
      rc = whereRangeSkipScanEst(pParse, pLower, pUpper, pLoop, &bDone);
      if( bDone ) return rc;
    }
  }
#else
  UNUSED_PARAMETER(pParse);
  UNUSED_PARAMETER(pBuilder);
#endif
  assert( pLower || pUpper );

  assert( pUpper==0 || (pUpper->wtFlags & TERM_VNULL)==0 );
  nNew = whereRangeAdjust(pLower, nOut);
  nNew = whereRangeAdjust(pUpper, nNew);

  /* TUNING: If there is both an upper and lower limit, assume the range is
  ** reduced by an additional 75%. This means that, by default, an open-ended
  ** range query (e.g. col > ?) is assumed to match 1/4 of the rows in the







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        rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq, &bOk);
        if( rc==SQLITE_OK && bOk ){
          tRowcnt iNew;
          whereKeyStats(pParse, p, pRec, 0, a);
          iNew = a[0] + ((pLower->eOperator & WO_GT) ? a[1] : 0);
          if( iNew>iLower ) iLower = iNew;
          nOut--;
          pLower = 0;
        }
      }

      /* If possible, improve on the iUpper estimate using ($P:$U). */
      if( pUpper ){
        int bOk;                    /* True if value is extracted from pExpr */
        Expr *pExpr = pUpper->pExpr->pRight;
................................................................................
        rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq, &bOk);
        if( rc==SQLITE_OK && bOk ){
          tRowcnt iNew;
          whereKeyStats(pParse, p, pRec, 1, a);
          iNew = a[0] + ((pUpper->eOperator & WO_LE) ? a[1] : 0);
          if( iNew<iUpper ) iUpper = iNew;
          nOut--;
          pUpper = 0;
        }
      }

      pBuilder->pRec = pRec;
      if( rc==SQLITE_OK ){
        if( iUpper>iLower ){
          nNew = sqlite3LogEst(iUpper - iLower);
        }else{
          nNew = 10;        assert( 10==sqlite3LogEst(2) );
        }
        if( nNew<nOut ){
          nOut = nNew;
        }

        WHERETRACE(0x10, ("range scan regions: %u..%u  est=%d\n",
                           (u32)iLower, (u32)iUpper, nOut));

      }
    }else{
      int bDone = 0;
      rc = whereRangeSkipScanEst(pParse, pLower, pUpper, pLoop, &bDone);
      if( bDone ) return rc;
    }
  }
#else
  UNUSED_PARAMETER(pParse);
  UNUSED_PARAMETER(pBuilder);

  assert( pLower || pUpper );
#endif
  assert( pUpper==0 || (pUpper->wtFlags & TERM_VNULL)==0 );
  nNew = whereRangeAdjust(pLower, nOut);
  nNew = whereRangeAdjust(pUpper, nNew);

  /* TUNING: If there is both an upper and lower limit, assume the range is
  ** reduced by an additional 75%. This means that, by default, an open-ended
  ** range query (e.g. col > ?) is assumed to match 1/4 of the rows in the

Changes to test/analyze9.test.

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  2 "d=0 AND a='z' AND b='n' AND e<100" {/*t5e (e<?)*/}

  3 "d=0 AND e<300"                     {/*t5d (d=?)*/}
  4 "d=0 AND e<200"                     {/*t5e (e<?)*/}
} {
  do_eqp_test 24.$tn "SeLeCt * FROM t5 WHERE $where" $eqp
}















































finish_test








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  2 "d=0 AND a='z' AND b='n' AND e<100" {/*t5e (e<?)*/}

  3 "d=0 AND e<300"                     {/*t5d (d=?)*/}
  4 "d=0 AND e<200"                     {/*t5e (e<?)*/}
} {
  do_eqp_test 24.$tn "SeLeCt * FROM t5 WHERE $where" $eqp
}

#-------------------------------------------------------------------------
# Test that if stat4 data is available but cannot be used because the
# rhs of a range constraint is a complex expression, the default estimates
# are used instead.
ifcapable stat4&&cte {
  do_execsql_test 25.1 {
    CREATE TABLE t6(a, b);
    WITH ints(i,j) AS (
      SELECT 1,1 UNION ALL SELECT i+1,j+1 FROM ints WHERE i<100
    ) INSERT INTO t6 SELECT * FROM ints;
    CREATE INDEX aa ON t6(a);
    CREATE INDEX bb ON t6(b);
    ANALYZE;
  }

  # Term (b<?) is estimated at 25%. Better than (a<30) but not as
  # good as (a<20).
  do_eqp_test 25.2.1 { SELECT * FROM t6 WHERE a<30 AND b<? } {
    0 0 0 {SEARCH TABLE t6 USING INDEX bb (b<?)}
  }
  do_eqp_test 25.2.2 { SELECT * FROM t6 WHERE a<20 AND b<? } {
    0 0 0 {SEARCH TABLE t6 USING INDEX aa (a<?)}
  }

  # Term (b BETWEEN ? AND ?) is estimated at 1/64.
  do_eqp_test 25.3.1 { 
    SELECT * FROM t6 WHERE a BETWEEN 5 AND 10 AND b BETWEEN ? AND ? 
  } {
    0 0 0 {SEARCH TABLE t6 USING INDEX bb (b>? AND b<?)}
  }
  
  # Term (b BETWEEN ? AND 60) is estimated to return roughly 15 rows -
  # 60 from (b<=60) multiplied by 0.25 for the b>=? term. Better than
  # (a<20) but not as good as (a<10).
  do_eqp_test 25.4.1 { 
    SELECT * FROM t6 WHERE a < 10 AND (b BETWEEN ? AND 60)
  } {
    0 0 0 {SEARCH TABLE t6 USING INDEX aa (a<?)}
  }
  do_eqp_test 25.4.2 { 
    SELECT * FROM t6 WHERE a < 20 AND (b BETWEEN ? AND 60)
  } {
    0 0 0 {SEARCH TABLE t6 USING INDEX bb (b>? AND b<?)}
  }
}

finish_test