| From: | Jeff Davis <pgsql(at)j-davis(dot)com> |
|---|---|
| To: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> |
| Cc: | Simon Riggs <simon(at)2ndQuadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, jd(at)commandprompt(dot)com, Gregory Stark <stark(at)enterprisedb(dot)com>, Mark Kirkwood <markir(at)paradise(dot)net(dot)nz>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Hot Standby (v9d) |
| Date: | 2009-01-28 20:55:54 |
| Message-ID: | 1233176154.5692.15.camel@dell.linuxdev.us.dell.com |
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| Lists: | pgsql-hackers |
On Wed, 2009-01-28 at 22:47 +0200, Heikki Linnakangas wrote:
> It's not quite that simple. Setting max_standby_delay=5mins means that
> you're willing to wait 5 minutes for each query to die. Which means that
> in worst case you have to stop for 5 minutes at every single vacuum
> record, and fall behind much more than 5 minutes.
Just trying to follow along: are you talking about the situation where
there are (for example) a continuous stream of "select pg_sleep(600)" on
the standby, and a series of rapid VACUUMs on the primary?
This situation might be more likely now that we have partial VACUUMs.
> It should also be noted that the control functions allow you to connect
> to the database and manually pause/resume the replay. So you can for
> example set max_standby_delay=0 during the day, but pause the replay
> manually before starting a nightly report.
>
That's a very cool feature.
Regards,
Jeff Davis
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