| Lists: | pgsql-hackers |
|---|
| From: | "Zeugswetter Andreas DCP SD" <ZeugswetterA(at)spardat(dot)at> |
|---|---|
| To: | "Mark Wong" <markw(at)osdl(dot)org>, <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: XLOG_BLCKSZ vs. wal_buffers table |
| Date: | 2006-05-02 15:00:58 |
| Message-ID: | E1539E0ED7043848906A8FF995BDA579FC3989@m0143.s-mxs.net |
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| Lists: | pgsql-hackers |
> I'm planning on continuing to increase XLOG_BLCKSZ and wal_buffers to
> determine when the throughput starts to level out or drop
I think for an even better comparison you should scale wal_buffers
down with increasing XLOG_BLCKSZ, so that the xlog buffer has a fixed
size in kb.
Reasonable wal_buffers imho amount to at least 256kb, better yet 512 or
1 Mb,
with sufficiently large transactions (and to try to factor out the
difference
between blocksizes).
Andreas
| From: | "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com> |
|---|---|
| To: | Zeugswetter Andreas DCP SD <ZeugswetterA(at)spardat(dot)at> |
| Cc: | Mark Wong <markw(at)osdl(dot)org>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: XLOG_BLCKSZ vs. wal_buffers table |
| Date: | 2006-05-02 17:07:38 |
| Message-ID: | 20060502170738.GX97354@pervasive.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Lists: | pgsql-hackers |
On Tue, May 02, 2006 at 05:00:58PM +0200, Zeugswetter Andreas DCP SD wrote:
>
> > I'm planning on continuing to increase XLOG_BLCKSZ and wal_buffers to
> > determine when the throughput starts to level out or drop
>
> I think for an even better comparison you should scale wal_buffers
> down with increasing XLOG_BLCKSZ, so that the xlog buffer has a fixed
> size in kb.
>
> Reasonable wal_buffers imho amount to at least 256kb, better yet 512 or
> 1 Mb,
> with sufficiently large transactions (and to try to factor out the
> difference
> between blocksizes).
AFAIK all the transactions in DBT2 are pretty small. I think all DML is
single-row in fact, so I'm not sure that having wal_buffers much larger
than the number of connections would help much.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461