| From: | Josh Berkus <josh(at)agliodbs(dot)com> |
|---|---|
| To: | Greg Smith <greg(at)2ndquadrant(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, Magnus Hagander <magnus(at)hagander(dot)net>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: auto-sizing wal_buffers |
| Date: | 2011-01-15 22:34:11 |
| Message-ID: | 4D3220E3.20804@agliodbs.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On 1/14/11 10:51 PM, Greg Smith wrote:
>
> ! Since the data is written out to disk at every transaction
> commit,
> ! the setting many only need to be be large enough to hold the
> amount
> ! of WAL data generated by one typical transaction. Larger values,
> ! typically at least a few megabytes, can improve write performance
> ! on a busy server where many clients are committing at once.
> ! Extremely large settings are unlikely to provide additional
> benefit.
I think we can be more specific on that last sentence; is there even any
*theoretical* benefit to settings above 16MB, the size of a WAL segment?
Certainly there have been no test results to show any.
If we don't know, keep it vague, but otherwise I suggest:
"Settings larger than the size of a single WAL segment (16MB by default)
are unlikely to produce any benefit."
--
-- Josh Berkus
PostgreSQL Experts Inc.
http://www.pgexperts.com
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Alex Hunsaker | 2011-01-15 22:48:28 | Re: arrays as pl/perl input arguments [PATCH] |
| Previous Message | Dimitri Fontaine | 2011-01-15 22:32:37 | Re: Include WAL in base backup |