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Fixes:

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I found another bug in btree index.  Looking at the code it seems that NULL
keys are never used to build or scan a btree index (see the explain commands
in the example).  However this is not the case when a null key is retrieved
in an outer loop of a join select and used in an index scan of an inner loop.
This bug causes at least three kinds of problems:

1)  the backend crashes when it tries to compare a text string with a null.

2)  it is not possible to find tuples with null keys in a join.

3)  null is considered equal to 0 when the datum is passed by value, see
    the last query.

Submitted by: Massimo Dal Zotto <dz@cs.unitn.it>
This commit is contained in:
Marc G. Fournier
1996-10-30 06:08:10 +00:00
parent 6ada9dfdce
commit 69c7f25bed
4 changed files with 43 additions and 5 deletions
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7
src/backend/executor/nodeIndexscan.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.1.1.1 1996/07/09 06:21:26 scrappy Exp $
* $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.2 1996/10/30 06:08:10 scrappy Exp $
*
*-------------------------------------------------------------------------
*/
@ -273,6 +273,11 @@ ExecIndexReScan(IndexScan *node, ExprContext *exprCtxt, Plan* parent)
scanvalue = (Datum)
ExecEvalExpr(scanexpr, exprCtxt, &isNull, &isDone);
scan_keys[j].sk_argument = scanvalue;
if (isNull) {
scan_keys[j].sk_flags |= SK_ISNULL;
} else {
scan_keys[j].sk_flags &= ~SK_ISNULL;
}
}
}
}