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Overview
Comment:Fix an error in estimating of the number of rows visited by a range scan.
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Timelines: family | ancestors | descendants | both | experimental-costs
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SHA1: d491de62fce69d93e89f65f7713972f7c2c451f7
User & Date: dan 2014-04-28 08:49:54.584
Context
2014-04-28
09:35
Modify internal function whereLoopAdjustCost() so that it does not prefer a skip-scan over a regular index scan even if the regular scan uses a subset of the WHERE terms used by the skip-scan. (check-in: 88a5758dcc user: dan tags: experimental-costs)
08:49
Fix an error in estimating of the number of rows visited by a range scan. (check-in: d491de62fc user: dan tags: experimental-costs)
2014-04-26
20:21
Fix an sqlite3_stmt_status() problem caused by recent changs on this branch. (check-in: dee2040924 user: dan tags: experimental-costs)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/where.c.
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    }

    nOutUnadjusted = pNew->nOut;
    pNew->rRun += nInMul + nIn;
    pNew->nOut += nInMul + nIn;
    whereLoopOutputAdjust(pBuilder->pWC, pNew);
    rc = whereLoopInsert(pBuilder, pNew);




    pNew->nOut = nOutUnadjusted;


    if( (pNew->wsFlags & WHERE_TOP_LIMIT)==0
     && pNew->u.btree.nEq<(pProbe->nKeyCol + (pProbe->zName!=0))
    ){
      whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nInMul+nIn);
    }
    pNew->nOut = saved_nOut;








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    }

    nOutUnadjusted = pNew->nOut;
    pNew->rRun += nInMul + nIn;
    pNew->nOut += nInMul + nIn;
    whereLoopOutputAdjust(pBuilder->pWC, pNew);
    rc = whereLoopInsert(pBuilder, pNew);

    if( pNew->wsFlags & WHERE_COLUMN_RANGE ){
      pNew->nOut = saved_nOut;
    }else{
      pNew->nOut = nOutUnadjusted;
    }

    if( (pNew->wsFlags & WHERE_TOP_LIMIT)==0
     && pNew->u.btree.nEq<(pProbe->nKeyCol + (pProbe->zName!=0))
    ){
      whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nInMul+nIn);
    }
    pNew->nOut = saved_nOut;
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Changes to test/cost.test.
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} {
  0 0 0 {SEARCH TABLE t5 USING INDEX t5b (b=?)} 
  0 0 0 {SEARCH TABLE t5 USING INDEX t5c (c=?)} 
  0 0 0 {SEARCH TABLE t5 USING INDEX t5d (d=?)} 
  0 0 0 {USE TEMP B-TREE FOR ORDER BY}
}



























finish_test











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} {
  0 0 0 {SEARCH TABLE t5 USING INDEX t5b (b=?)} 
  0 0 0 {SEARCH TABLE t5 USING INDEX t5c (c=?)} 
  0 0 0 {SEARCH TABLE t5 USING INDEX t5d (d=?)} 
  0 0 0 {USE TEMP B-TREE FOR ORDER BY}
}

#-------------------------------------------------------------------------
# If there is no likelihood() or stat3 data, SQLite assumes that a closed
# range scan (e.g. one constrained by "col BETWEEN ? AND ?" constraint)
# visits 1/16 of the rows in a table.
#
# Note: 1/17 =~ 0.058
# Note: 1/15 =~ 0.067
#
reset_db
do_execsql_test 4.1 {
  CREATE TABLE t1(a, b);
  CREATE INDEX i1 ON t1(a);
  CREATE INDEX i2 ON t1(b);
}
do_eqp_test 4.2 {
  SELECT * FROM t1 WHERE likelihood(a=?, 0.058) AND b BETWEEN ? AND ?;
} {
  0 0 0 {SEARCH TABLE t1 USING INDEX i1 (a=?)}
}
do_eqp_test 4.3 {
  SELECT * FROM t1 WHERE likelihood(a=?, 0.067) AND b BETWEEN ? AND ?;
} {
  0 0 0 {SEARCH TABLE t1 USING INDEX i2 (b>? AND b<?)}
}


finish_test