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Overview
Comment:Fix a problem in the omit-table-from-left-join optimization from check-in [0cd82ee9a8413cf] that was discovered by OSSFuzz.
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SHA3-256:b016c28fa5617a20ad34c005372e738d28f7fc4388d19ee0cb7add4ed19d74aa
User & Date: drh 2017-11-23 04:45:35
Context
2017-11-24
16:55
Enhance the configure script to detect zLib. check-in: e3b6e220 user: drh tags: trunk
2017-11-23
04:45
Fix a problem in the omit-table-from-left-join optimization from check-in [0cd82ee9a8413cf] that was discovered by OSSFuzz. check-in: b016c28f user: drh tags: trunk
00:45
Completely disable the skip-ahead-distinct optimization for all but the inner-most loop of a DISTINCT join. Fix for ticket [ef9318757b152e3a26e9592] check-in: b7595cf2 user: drh tags: trunk
Changes
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Changes to src/where.c.

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  **
  ** or from:
  **
  **     SELECT DISTINCT v1, v3 FROM t1 
  **       LEFT JOIN t2
  **       LEFT JOIN t3 USING (t1.ipk=t3.ipk)
  */

  if( pWInfo->nLevel>=2
   && pResultSet!=0               /* guarantees condition (1) above */
   && OptimizationEnabled(db, SQLITE_OmitNoopJoin)
  ){
    int i;
    Bitmask tabUsed = sqlite3WhereExprListUsage(pMaskSet, pResultSet);
    if( sWLB.pOrderBy ){
................................................................................
          ){
            break;
          }
        }
      }
      if( pTerm<pEnd ) continue;
      WHERETRACE(0xffff, ("-> drop loop %c not used\n", pLoop->cId));






      if( i!=pWInfo->nLevel-1 ){
        int nByte = (pWInfo->nLevel-1-i) * sizeof(WhereLevel);
        memmove(&pWInfo->a[i], &pWInfo->a[i+1], nByte);
      }
      pWInfo->nLevel--;
      nTabList--;
    }
................................................................................
  pWInfo->iTop = sqlite3VdbeCurrentAddr(v);
  if( db->mallocFailed ) goto whereBeginError;

  /* Generate the code to do the search.  Each iteration of the for
  ** loop below generates code for a single nested loop of the VM
  ** program.
  */
  notReady = ~(Bitmask)0;
  for(ii=0; ii<nTabList; ii++){
    int addrExplain;
    int wsFlags;
    pLevel = &pWInfo->a[ii];
    wsFlags = pLevel->pWLoop->wsFlags;
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
    if( (pLevel->pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0 ){







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  **
  ** or from:
  **
  **     SELECT DISTINCT v1, v3 FROM t1 
  **       LEFT JOIN t2
  **       LEFT JOIN t3 USING (t1.ipk=t3.ipk)
  */
  notReady = ~(Bitmask)0;
  if( pWInfo->nLevel>=2
   && pResultSet!=0               /* guarantees condition (1) above */
   && OptimizationEnabled(db, SQLITE_OmitNoopJoin)
  ){
    int i;
    Bitmask tabUsed = sqlite3WhereExprListUsage(pMaskSet, pResultSet);
    if( sWLB.pOrderBy ){
................................................................................
          ){
            break;
          }
        }
      }
      if( pTerm<pEnd ) continue;
      WHERETRACE(0xffff, ("-> drop loop %c not used\n", pLoop->cId));
      notReady &= ~pLoop->maskSelf;
      for(pTerm=sWLB.pWC->a; pTerm<pEnd; pTerm++){
        if( (pTerm->prereqAll & pLoop->maskSelf)!=0 ){
          pTerm->wtFlags |= TERM_CODED;
        }
      }
      if( i!=pWInfo->nLevel-1 ){
        int nByte = (pWInfo->nLevel-1-i) * sizeof(WhereLevel);
        memmove(&pWInfo->a[i], &pWInfo->a[i+1], nByte);
      }
      pWInfo->nLevel--;
      nTabList--;
    }
................................................................................
  pWInfo->iTop = sqlite3VdbeCurrentAddr(v);
  if( db->mallocFailed ) goto whereBeginError;

  /* Generate the code to do the search.  Each iteration of the for
  ** loop below generates code for a single nested loop of the VM
  ** program.
  */

  for(ii=0; ii<nTabList; ii++){
    int addrExplain;
    int wsFlags;
    pLevel = &pWInfo->a[ii];
    wsFlags = pLevel->pWLoop->wsFlags;
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
    if( (pLevel->pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0 ){

Changes to test/join2.test.

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do_eqp_test 4.2.2 {
  SELECT v1, v3 FROM c1 LEFT JOIN c2 ON (c2.k=v1) LEFT JOIN c3 ON (c3.k=v1+1);
} {
  0 0 0 {SCAN TABLE c1} 
  0 1 2 {SEARCH TABLE c3 USING INTEGER PRIMARY KEY (rowid=?)}
}
























finish_test







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do_eqp_test 4.2.2 {
  SELECT v1, v3 FROM c1 LEFT JOIN c2 ON (c2.k=v1) LEFT JOIN c3 ON (c3.k=v1+1);
} {
  0 0 0 {SCAN TABLE c1} 
  0 1 2 {SEARCH TABLE c3 USING INTEGER PRIMARY KEY (rowid=?)}
}

# 2017-11-23 (Thanksgiving day)
# OSSFuzz found an assertion fault in the new LEFT JOIN eliminator code.
#
do_execsql_test 4.3.0 {
  DROP TABLE IF EXISTS t1;
  DROP TABLE IF EXISTS t2;
  CREATE TABLE t1(x PRIMARY KEY) WITHOUT ROWID;
  CREATE TABLE t2(x);
  SELECT a.x
    FROM t1 AS a
    LEFT JOIN t1 AS b ON (a.x=b.x)
    LEFT JOIN t2 AS c ON (a.x=c.x);
} {}
do_execsql_test 4.3.1 {
  WITH RECURSIVE c(x) AS (VALUES(1) UNION ALL SELECT x+1 FROM c WHERE x<10)
    INSERT INTO t1(x) SELECT x FROM c;
  INSERT INTO t2(x) SELECT x+9 FROM t1;
  SELECT a.x, c.x
    FROM t1 AS a
    LEFT JOIN t1 AS b ON (a.x=b.x)
    LEFT JOIN t2 AS c ON (a.x=c.x);
} {1 {} 2 {} 3 {} 4 {} 5 {} 6 {} 7 {} 8 {} 9 {} 10 10}

finish_test