From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
Cc: | "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>, Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>, Gavin Sherry <swm(at)linuxworld(dot)com(dot)au>, Philip Yarra <philip(at)utiba(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: tablespaces and non-empty directories |
Date: | 2005-11-23 04:16:16 |
Message-ID: | 10220.1132719376@sss.pgh.pa.us |
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Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> Jim C. Nasby wrote:
>> Along those lines, is there anything else that would benefit from being
>> moved? pg_clog and pg_subtrans come to mind; but maybe pg_multixact and
>> pg_twophase are candidates as well?
> Hmm, I doubt moving any of the SLRU files (clog, subtrans, multixact)
> will have much of an impact.
Certainly pushing them onto the WAL spindle would be a serious misstep.
There is a good case for giving WAL its own dedicated disk --- there is
no case that I've seen for giving any of these their own disk.
> If there's too much I/O on those, a better
> solution would be to increase the number of buffers allocated to them.
> Currently we use 8 for all of them which is probably not appropiate for
> everyone.
I've just been looking at a test case provided by Rob Creager that
causes some pretty severe contention on SubtransControlLock. There
are a number of possible answers to this, but increasing the number of
pg_subtrans buffers is definitely one of them. I think it's probably
time we got rid of the assumption that all the uses of slru.c should
have the same number of buffers ...
regards, tom lane
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