From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Assaf Arkin <arkin(at)exoffice(dot)com> |
Cc: | Peter Mount <petermount(at)it(dot)maidstone(dot)gov(dot)uk>, pgsql-interfaces(at)hub(dot)org |
Subject: | Re: [INTERFACES] Transaction support in 6.5.3/JDBC |
Date: | 1999-12-09 01:00:32 |
Message-ID: | 29070.944701232@sss.pgh.pa.us |
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Lists: | pgsql-interfaces |
Assaf Arkin <arkin(at)exoffice(dot)com> writes:
> I have a very simple test. I start two threads, both of them attempt to
> do an update on the exact same row in the table, both connections keep
> hanging.
Hmm. The backend doesn't have any trouble detecting this; I checked
both current sources and 6.5.3:
play=> select * from z1;
f1
--
1
2
(2 rows)
play=> begin;
BEGIN
play=> update z1 set f1 = 3 where f1 = 1;
UPDATE 1
<now in a second psql do>
play=> begin;
BEGIN
play=> update z1 set f1 = 4 where f1 = 2;
UPDATE 1
play=> update z1 set f1 = 3 where f1 = 1;
<second psql is now waiting for first one to commit or abort>
<back in first psql do>
play=> update z1 set f1 = 4 where f1 = 2;
After a second or so, one psql will say
NOTICE: Deadlock detected -- See the lock(l) manual page for a possible cause.
ERROR: WaitOnLock: error on wakeup - Aborting this transaction
and the other will say
UPDATE 1
If you're not getting this behavior, then either your test code is wrong
or there's something broken in the JDBC driver...
regards, tom lane
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