| From: | Dimitri Fontaine <dfontaine(at)hi-media(dot)com> |
|---|---|
| To: | Bruce Momjian <bruce(at)momjian(dot)us> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Greg Stark <gsstark(at)mit(dot)edu>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Hot Standby query cancellation and Streaming Replication integration |
| Date: | 2010-02-26 22:11:28 |
| Message-ID: | m2iq9jtzov.fsf@hi-media.com |
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| Lists: | pgsql-hackers |
Bruce Momjian <bruce(at)momjian(dot)us> writes:
> Doesn't the system already adjust the delay based on the length of slave
> transactions, e.g. max_standby_delay. It seems there is no need for a
> user switch --- just max_standby_delay really high.
Well that GUC looks like it allows to set a compromise between HA and
reporting, not to say "do not ever give the priority to the replay while
I'm running my reports". At least that's how I understand it.
The feedback loop might get expensive on master server when running
reporting queries on the slave, unless you can "pause" it explicitly I
think. I don't see how the system will guess that you're running a
reporting server rather than a HA node, and max_standby_delay is just a
way to tell the standby to please be nice in case of abuse.
Regards,
--
dim
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