| From: | Martin Pihlak <martin(dot)pihlak(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Magnus Hagander <magnus(at)hagander(dot)net>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: reducing statistics write overhead |
| Date: | 2008-09-08 13:25:20 |
| Message-ID: | 48C527C0.2070707@gmail.com |
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| Lists: | pgsql-hackers |
Tom Lane wrote:
> Timestamp within the file is certainly better than trying to rely on
> filesystem timestamps. I doubt 1 sec resolution is good enough, and
> I'd also be worried about issues like clock skew between the
> postmaster's time and the filesystem's time.
>
Attached is a patch which adds a timestamp to pgstat.stat file header,
backend_read_statsfile uses this to determine if the file is fresh.
During the wait loop, the stats request message is retransmitted to
compensate for possible loss of message(s).
The collector only writes the file mostly at PGSTAT_STAT_INTERVAL frequency,
currently no extra custom timeouts can be passed in the message. This can
of course be added if need arises.
regards,
Martin
| Attachment | Content-Type | Size |
|---|---|---|
| stat-write.patch | text/x-diff | 11.9 KB |
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