| From: | Greg Smith <greg(at)2ndquadrant(dot)com> |
|---|---|
| To: | Bruce Momjian <bruce(at)momjian(dot)us> |
| Cc: | Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: max_standby_delay considered harmful |
| Date: | 2010-05-06 21:26:14 |
| Message-ID: | 4BE333F6.5080704@2ndquadrant.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Bruce Momjian wrote:
> Remember, delaying wal application just delays making the standby a
> master and makes the slave data appear staler. We can just tell people
> that the larger their queries are, the larger this delay will be. If
> they want to control this, they can set 'statement_timeout' already.
>
While a useful defensive component, statement_timeout is a user setting,
so it can't provide guaranteed protection against a WAL application
denial of service from a long running query. A user that overrides the
system setting and kicks off a long query puts you right back into
needing a timeout to ensure forward progress of standby replay.
--
Greg Smith 2ndQuadrant US Baltimore, MD
PostgreSQL Training, Services and Support
greg(at)2ndQuadrant(dot)com www.2ndQuadrant.us
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Merlin Moncure | 2010-05-06 21:29:34 | Re: SELECT * in a CREATE VIEW statement doesn't update column set automatically |
| Previous Message | Bruce Momjian | 2010-05-06 21:01:04 | Re: max_standby_delay considered harmful |