| From: | Josh Berkus <josh(at)agliodbs(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)2ndquadrant(dot)com> |
| Cc: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Andrew Dunstan <andrew(at)dunslane(dot)net>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: assertion failure 9.3.4 |
| Date: | 2014-04-22 21:49:00 |
| Message-ID: | 5356E3CC.7000104@agliodbs.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
>> In order to encounter this issue, I'd need to have two concurrent
>> processes update the child records of the same parent record? That is:
>>
>> A ---> B1
>> \---> B2
>>
>> ... and the issue should only happen if I update both B1 and B2
>> concurrently in separate sessions?
>
> I don't think that'll trigger it. You need rows that are first key share
> locked and then updated by the locking transaction. Under
> concurrency. And the timewindow really is rather small..
Well, currently I have a test which locks A and B1, then updates B1
(twice, actually), and then updates A. However, since there's a lock on
A, there's no concurrent updating of B1 and B2. This is based on the
behavior of the queue where I originally saw the problem, but it doesn't
reproduce the bug.
I'm thinking I need to just lock B1, update B1, then A, while allowing a
concurrent session to update B2 and and A. No?
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Andres Freund | 2014-04-22 21:51:58 | Re: assertion failure 9.3.4 |
| Previous Message | Andres Freund | 2014-04-22 21:46:57 | Re: assertion failure 9.3.4 |