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Overview
Comment:When doing the optimization that attempts to avoid sorting on a GROUP BY, do not assume that the values in an index on an expression are non-NULL. Bug discovered by Wang Ke's fuzzer and reported at forum post 74330094d8.
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SHA3-256: 7178dc3a32c3a4a33e437fd5026f6f72e4809ceb7d2cd12a25a74b80d5c95d33
User & Date: drh 2021-04-26 14:32:48
Context
2021-04-26
15:28
More aggressive detection of OOM errors in resolveAlias(). dbsqlfuzz 7f96832c2ef7ee472022ed805b064e55e41094b2 (check-in: e99faf4f user: drh tags: trunk)
14:32
When doing the optimization that attempts to avoid sorting on a GROUP BY, do not assume that the values in an index on an expression are non-NULL. Bug discovered by Wang Ke's fuzzer and reported at forum post 74330094d8. (check-in: 7178dc3a user: drh tags: trunk)
14:09
Do not initialize eponymous virtual tables when parsing the schema. This can happen if the db is corrupt. (check-in: cb8c41aa user: dan tags: trunk)
Changes
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Changes to src/where.c.

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        return 0;
      }else{
        nKeyCol = pIndex->nKeyCol;
        nColumn = pIndex->nColumn;
        assert( nColumn==nKeyCol+1 || !HasRowid(pIndex->pTable) );
        assert( pIndex->aiColumn[nColumn-1]==XN_ROWID
                          || !HasRowid(pIndex->pTable));




        isOrderDistinct = IsUniqueIndex(pIndex)
                          && (pLoop->wsFlags & WHERE_SKIPSCAN)==0;
      }

      /* Loop through all columns of the index and deal with the ones
      ** that are not constrained by == or IN.
      */







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        return 0;
      }else{
        nKeyCol = pIndex->nKeyCol;
        nColumn = pIndex->nColumn;
        assert( nColumn==nKeyCol+1 || !HasRowid(pIndex->pTable) );
        assert( pIndex->aiColumn[nColumn-1]==XN_ROWID
                          || !HasRowid(pIndex->pTable));
        /* All relevant terms of the index must also be non-NULL in order
        ** for isOrderDistinct to be true.  So the isOrderDistint value
        ** computed here might be a false positive.  Corrections will be
        ** made at tag-20210426-1 below */
        isOrderDistinct = IsUniqueIndex(pIndex)
                          && (pLoop->wsFlags & WHERE_SKIPSCAN)==0;
      }

      /* Loop through all columns of the index and deal with the ones
      ** that are not constrained by == or IN.
      */
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          if( iColumn==pIndex->pTable->iPKey ) iColumn = XN_ROWID;
        }else{
          iColumn = XN_ROWID;
          revIdx = 0;
        }

        /* An unconstrained column that might be NULL means that this
        ** WhereLoop is not well-ordered
        */
        if( isOrderDistinct
         && iColumn>=0
         && j>=pLoop->u.btree.nEq
         && pIndex->pTable->aCol[iColumn].notNull==0
        ){
          isOrderDistinct = 0;
        }





        /* Find the ORDER BY term that corresponds to the j-th column
        ** of the index and mark that ORDER BY term off 
        */
        isMatch = 0;
        for(i=0; bOnce && i<nOrderBy; i++){
          if( MASKBIT(i) & obSat ) continue;







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          if( iColumn==pIndex->pTable->iPKey ) iColumn = XN_ROWID;
        }else{
          iColumn = XN_ROWID;
          revIdx = 0;
        }

        /* An unconstrained column that might be NULL means that this
        ** WhereLoop is not well-ordered.  tag-20210426-1
        */
        if( isOrderDistinct ){
          if( iColumn>=0
           && j>=pLoop->u.btree.nEq
           && pIndex->pTable->aCol[iColumn].notNull==0
          ){
            isOrderDistinct = 0;
          }
          if( iColumn==XN_EXPR ){
            isOrderDistinct = 0;
          }
        } 

        /* Find the ORDER BY term that corresponds to the j-th column
        ** of the index and mark that ORDER BY term off 
        */
        isMatch = 0;
        for(i=0; bOnce && i<nOrderBy; i++){
          if( MASKBIT(i) & obSat ) continue;

Changes to test/select5.test.

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#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing aggregate functions and the
# GROUP BY and HAVING clauses of SELECT statements.
#
# $Id: select5.test,v 1.20 2008/08/21 14:15:59 drh Exp $

set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Build some test data
#
execsql {







<







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#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing aggregate functions and the
# GROUP BY and HAVING clauses of SELECT statements.
#


set testdir [file dirname $argv0]
source $testdir/tester.tcl

# Build some test data
#
execsql {
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} {two 3 one 6}
do_test select5-8.8 {
  execsql {
    SELECT a, count(*) FROM t8a, t8b GROUP BY a ORDER BY 2;
  }
} {two 3 one 9}









 
finish_test







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} {two 3 one 6}
do_test select5-8.8 {
  execsql {
    SELECT a, count(*) FROM t8a, t8b GROUP BY a ORDER BY 2;
  }
} {two 3 one 9}

# 2021-04-26 forum https://sqlite.org/forum/forumpost/74330094d8
reset_db
do_execsql_test select5-9.1 {
  CREATE TABLE t1(a INT, b INT);
  INSERT INTO t1(a,b) VALUES(1,null),(null,null),(1,null);
  CREATE UNIQUE INDEX t1b ON t1(abs(b));
  SELECT quote(a), quote(b), '|' FROM t1 GROUP BY a, abs(b);
} {NULL NULL | 1 NULL |}

finish_test