Re: [HACKERS] latest snapshot crashes backend

> > Care to give us a table:
> > select * from pg_shadow where (usesysid is null and oid is null);
>
> Sure, that's easy. Just negate your where clause:
>
> tgl=> select * from pg_shadow
> tgl-> where not (usesysid is null and oid is null);
> pqReadData() -- backend closed the channel unexpectedly.
>
> If you can reproduce this, will you have a chance to look at it? I don't
> know where the problem is, but suspect that it is farther back than the
> parser transformations. Rewrite system, optimizer, or executor??
>

OK, here is the fix. I am not applying it yet until 6.4 is released by
Marc, OK? In fact, I am not sure how we are going to do patch
application after 6.4, so would someone else please apply this?

---------------------------------------------------------------------------

*** ./backend/optimizer/path/clausesel.c.orig Wed Nov 4 16:49:35 1998
--- ./backend/optimizer/path/clausesel.c Wed Nov 4 17:11:02 1998
***************
*** 254,259 ****
--- 254,264 ----
*/
s1 = 0.1;
}
+ else if (not_clause((Node *) clause))
+ {
+ /* negate this baby */
+ return 1 - compute_selec(root, ((Expr *)clause)->args, or_selectivities);
+ }
else if (is_subplan((Node *) clause))
{

--
Bruce Momjian | http://www.op.net/~candle
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