Re: 8.3.0 backend segfaults - Mailing list pgsql-bugs

From Alex Hunsaker
Subject Re: 8.3.0 backend segfaults
Date
Msg-id 34d269d40803120858k33f7bfcfw855582b187862fcc@mail.gmail.com
Whole thread Raw
In response to Re: 8.3.0 backend segfaults  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: 8.3.0 backend segfaults
Re: 8.3.0 backend segfaults
List pgsql-bugs
On Wed, Mar 12, 2008 at 9:49 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> "Alex Hunsaker" <badalex@gmail.com> writes:
>  > On Wed, Mar 12, 2008 at 12:44 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> >> If you say "none of my stuff is changing any schemas", then I'd guess
>  >> that the triggering event is a background autovacuum, which forces
>  >> replan just like an intentional schema change would.  Does stopping
>  >> autovacuum make the problem go away?
>
>  > Yep turning off autovacuum seems to have fixed it.  And once I
>  > manually vacuum analyze workers; it blows up almost instantly.
>
>  Yeah, I was going to suggest that you ought to be able to extract
>  a test case involving doing a manual vacuum in between prepare and
>  execute.  I suspect it wouldn't even need to involve more than one
>  session.

Here is what im trying right now with no success:

3 clients doing this:
while(1)
{
        $db->begin_work();
        my $sth = $db->prepare_cached('select * from junk left join
junk as j on j.junk = junk.junk where junk.junk like ? limit 1;');
        print "VAC!\n";
        sleep 10;
        print "EX!\n";
        $sth->execute('junk') || die "failed: $!";
        $sth->fetchall_arrayref();
        $db->commit();
        $db->{'AutoCommit'} = 0;
        $db->{'AutoCommit'} = 1;
}

where when it prints VAC I :
update junk set junk = 'junkab';
VACUUM ANALYZE verbose junk;
(also tried deleting, and inserting a bunch of junk...)

3 other clients doing:
while(1)
{
        $db->begin_work();
        my $sth = $db->prepare_cached('select * from junk left join
junk as j on j.junk = junk.junk where junk.junk like ? limit 1;');
        $sth->execute('junk') || die "failed: $!";
        $sth->fetchall_arrayref();
        $db->rollback();
}

\d junk
    Table "public.junk"
 Column | Type | Modifiers
--------+------+-----------
 junk   | text |

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