| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Heikki Linnakangas <heikki(at)enterprisedb(dot)com> |
| Cc: | Robert Treat <xzilla(at)users(dot)sourceforge(dot)net>, pgsql-patches(at)postgresql(dot)org, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Greg Smith <gsmith(at)gregsmith(dot)com>, Theo Schlossnagle <jesus(at)omniti(dot)com>, "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com> |
| Subject: | Re: Expose checkpoint start/finish times into SQL. |
| Date: | 2008-04-05 18:00:15 |
| Message-ID: | 20080405180015.GC12256@alvh.no-ip.org |
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| Lists: | pgsql-patches |
Heikki Linnakangas wrote:
> Robert Treat wrote:
>> 2) Can be graphed over time (using rrdtool and others) for trending
>> checkpoint activity
>
> Hmm. You'd need the historical data to do that properly. In particular,
> if two checkpoints happen between the polling interval, you'd miss that.
Yes, Munin and other tools collect the values over time to create the
graph. It's not like "top" saves historical system load data either,
yet the collector is able to present you with a graph.
> log_checkpoints=on, in CSV output, seems like a better approach for that.
It's not, because the tool would have a much harder time trolling the
logs. CSV does not really make it much easier -- the DBA is still
tasked with importing the thing after the current file is complete; and
you don't have an up-to-date picture either.
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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