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Overview
Comment:Adjustments to the cost computation for the skip-scan query plan, to take into account the fact that a seek has to occur on each skip.
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SHA1: 0769eebd028ce31375cf93509a1d3687f7b117eb
User & Date: drh 2014-03-10 20:12:31
Context
2014-03-11
09:19
Add a test to see what happens if an rtree constructor encounters an SQLITE_BUSY error. No changes to code. check-in: 5527e23636 user: dan tags: trunk
01:48
Version 3.8.4 for sessions (plus two minor fixes). check-in: 917c410808 user: drh tags: sessions
2014-03-10
20:12
Adjustments to the cost computation for the skip-scan query plan, to take into account the fact that a seek has to occur on each skip. check-in: 0769eebd02 user: drh tags: trunk
18:03
Attempt to work around MSVC's treatment of __LINE__ as a non-constant value in "Edit and Continue" mode by avoiding the use of __LINE__ when SQLITE_VDBE_COVERAGE is not defined. check-in: 0a5318bc27 user: drh tags: trunk
Changes
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Changes to src/where.c.

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  ){
    LogEst nIter;
    pNew->u.btree.nEq++;
    pNew->u.btree.nSkip++;
    pNew->aLTerm[pNew->nLTerm++] = 0;
    pNew->wsFlags |= WHERE_SKIPSCAN;
    nIter = sqlite3LogEst(pProbe->aiRowEst[0]/pProbe->aiRowEst[saved_nEq+1]);


    whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nIter);

  }
  for(; rc==SQLITE_OK && pTerm!=0; pTerm = whereScanNext(&scan)){
    int nIn = 0;
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
    int nRecValid = pBuilder->nRecValid;
#endif
    if( (pTerm->eOperator==WO_ISNULL || (pTerm->wtFlags&TERM_VNULL)!=0)







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  ){
    LogEst nIter;
    pNew->u.btree.nEq++;
    pNew->u.btree.nSkip++;
    pNew->aLTerm[pNew->nLTerm++] = 0;
    pNew->wsFlags |= WHERE_SKIPSCAN;
    nIter = sqlite3LogEst(pProbe->aiRowEst[0]/pProbe->aiRowEst[saved_nEq+1]);
    pNew->rRun = rLogSize + nIter;
    pNew->nOut += nIter;
    whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nIter);
    pNew->nOut = saved_nOut;
  }
  for(; rc==SQLITE_OK && pTerm!=0; pTerm = whereScanNext(&scan)){
    int nIn = 0;
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
    int nRecValid = pBuilder->nRecValid;
#endif
    if( (pTerm->eOperator==WO_ISNULL || (pTerm->wtFlags&TERM_VNULL)!=0)

Changes to test/skipscan1.test.

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  SELECT i FROM t4 WHERE c=3;
  SELECT i FROM t4 WHERE d=4;
  SELECT i FROM t4 WHERE e=5;
  SELECT i FROM t4 WHERE f=6;
  SELECT i FROM t4 WHERE g=7;
  SELECT i FROM t4 WHERE h=8;
} {9 9 9 9 9 9 9 9}







































finish_test








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  SELECT i FROM t4 WHERE c=3;
  SELECT i FROM t4 WHERE d=4;
  SELECT i FROM t4 WHERE e=5;
  SELECT i FROM t4 WHERE f=6;
  SELECT i FROM t4 WHERE g=7;
  SELECT i FROM t4 WHERE h=8;
} {9 9 9 9 9 9 9 9}

# Make sure skip-scan cost computation in the query planner takes into
# account the fact that the seek must occur multiple times.
#
# Prior to 2014-03-10, the costs were computed incorrectly which would
# cause index t5i2 to be used instead of t5i1 on the skipscan1-5.3.
#
do_execsql_test skipscan1-5.1 {
  CREATE TABLE t5(
    id INTEGER PRIMARY KEY,
    loc TEXT,
    lang INTEGER,
    utype INTEGER,
    xa INTEGER,
    xd INTEGER,
    xh INTEGER
  );
  CREATE INDEX t5i1 on t5(loc, xh, xa, utype, lang);
  CREATE INDEX t5i2 ON t5(xd,loc,utype,lang);
  EXPLAIN QUERY PLAN
    SELECT xh, loc FROM t5 WHERE loc >= 'M' AND loc < 'N';
} {/.*COVERING INDEX t5i1 .*/}
do_execsql_test skipscan1-5.2 {
  ANALYZE;
  DELETE FROM sqlite_stat1;
  DROP TABLE IF EXISTS sqlite_stat4;
  DROP TABLE IF EXISTS sqlite_stat3;
  INSERT INTO sqlite_stat1 VALUES('t5','t5i1','2702931 3 2 2 2 2');
  INSERT INTO sqlite_stat1 VALUES('t5','t5i2','2702931 686 2 2 2');
  ANALYZE sqlite_master;
} {}
db cache flush
do_execsql_test skipscan1-5.3 {
  EXPLAIN QUERY PLAN
    SELECT xh, loc FROM t5 WHERE loc >= 'M' AND loc < 'N';
} {/.*COVERING INDEX t5i1 .*/}



finish_test