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Comment:Make sure the WhereLoop.aLTerm[] array is large enough when processing the skip-scan optimization. Fix for ticket [520070ec7fbaac].
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SHA1: ac5852d6403c9c9628ca0aa7be135c702f000698
User & Date: drh 2013-12-23 15:35:54
Context
2014-01-15
00:24
Merge recent fixes from trunk. Cherrypick of [c43b59dac1], [a221aa82bb], [e1eba1fb09], and [1e131094b5]. check-in: c697d2f8 user: mistachkin tags: branch-3.8.2
2013-12-23
15:35
Make sure the WhereLoop.aLTerm[] array is large enough when processing the skip-scan optimization. Fix for ticket [520070ec7fbaac]. check-in: ac5852d6 user: drh tags: branch-3.8.2
2013-12-22
20:44
Make sure the WhereLoop.aLTerm[] array is large enough when processing the skip-scan optimization. Fix for ticket [520070ec7fbaac]. check-in: 46d04059 user: drh tags: trunk
2013-12-06
14:53
Version 3.8.2 check-in: 27392118 user: dan tags: trunk, release, version-3.8.2
Changes
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Changes to src/where.c.

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  ** number 18 was found by experimentation to be the payoff point where
  ** skip-scan become faster than a full-scan.
  */
  if( pTerm==0
   && saved_nEq==saved_nSkip
   && saved_nEq+1<pProbe->nKeyCol
   && pProbe->aiRowEst[saved_nEq+1]>=18  /* TUNING: Minimum for skip-scan */

  ){
    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]);







>







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  ** number 18 was found by experimentation to be the payoff point where
  ** skip-scan become faster than a full-scan.
  */
  if( pTerm==0
   && saved_nEq==saved_nSkip
   && saved_nEq+1<pProbe->nKeyCol
   && pProbe->aiRowEst[saved_nEq+1]>=18  /* TUNING: Minimum for skip-scan */
   && (rc = whereLoopResize(db, pNew, pNew->nLTerm+1))==SQLITE_OK
  ){
    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]);

Changes to test/skipscan1.test.

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  EXPLAIN QUERY PLAN
  SELECT a,b,c,d,'|' FROM t3 WHERE b=345 ORDER BY a;
} {/* INDEX sqlite_autoindex_t3_1 (ANY(a) AND b=?)*/}
do_execsql_test skipscan1-3.2sort {
  EXPLAIN QUERY PLAN
  SELECT a,b,c,d,'|' FROM t3 WHERE b=345 ORDER BY a;
} {~/*ORDER BY*/}























finish_test








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  EXPLAIN QUERY PLAN
  SELECT a,b,c,d,'|' FROM t3 WHERE b=345 ORDER BY a;
} {/* INDEX sqlite_autoindex_t3_1 (ANY(a) AND b=?)*/}
do_execsql_test skipscan1-3.2sort {
  EXPLAIN QUERY PLAN
  SELECT a,b,c,d,'|' FROM t3 WHERE b=345 ORDER BY a;
} {~/*ORDER BY*/}

# Ticket 520070ec7fbaac: Array overrun in the skip-scan optimization
# 2013-12-22
#
do_execsql_test skipscan1-4.1 {
  CREATE TABLE t4(a,b,c,d,e,f,g,h,i);
  CREATE INDEX t4all ON t4(a,b,c,d,e,f,g,h);
  INSERT INTO t4 VALUES(1,2,3,4,5,6,7,8,9);
  ANALYZE;
  DELETE FROM sqlite_stat1;
  INSERT INTO sqlite_stat1 
    VALUES('t4','t4all','655360 163840 40960 10240 2560 640 160 40 10');
  ANALYZE sqlite_master;
  SELECT i FROM t4 WHERE a=1;
  SELECT i FROM t4 WHERE b=2;
  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