From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
---|---|
To: | Josh Berkus <josh(at)agliodbs(dot)com> |
Cc: | Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Keepalive for max_standby_delay |
Date: | 2010-05-27 17:26:26 |
Message-ID: | 1274981186.4405.100.camel@ebony |
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Lists: | pgsql-hackers |
On Wed, 2010-05-26 at 16:22 -0700, Josh Berkus wrote:
> > Just this second posted about that, as it turns out.
> >
> > I have a v3 *almost* ready of the keepalive patch. It still makes sense
> > to me after a few days reflection, so is worth discussion and review. In
> > or out, I want this settled within a week. Definitely need some R&R
> > here.
>
> Does the keepalive fix all the issues with max_standby_delay? Tom?
OK, here's v4.
Summary
* WALSender adds a timestamp onto the header of every WAL chunk sent.
* Each WAL record now has a conceptual "send timestamp" that remains
constant while that record is replayed. This is used as the basis from
which max_standby_delay is calculated when required during replay.
* Send timestamp is calculated as the later of the timestamp of chunk in
which WAL record was sent and the latest XLog time.
* WALSender sends an empty message as a keepalive when nothing else to
send. (No longer a special message type for the keepalive).
I think its close, but if there's a gaping hole here somewhere then I'll
punt for this release.
--
Simon Riggs www.2ndQuadrant.com
Attachment | Content-Type | Size |
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hs_keepalive.v4.patch | text/x-patch | 17.0 KB |
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