From: Richard Huxton <dev@archonet.com>
To: Din Adrian <adrian.din@easynet.ro>
Cc: Postgresql Performance <pgsql-performance@postgresql.org>
Subject: Re: Tunning postgresql on linux (fedora core 3)
Date: Thu, 03 Feb 2005 14:52:04 +0000
Message-ID: <42023A94.5040904@archonet.com> (raw)
In-Reply-To: <opslmpx0u3awcxfg@adi>
References: <opsll8h2shawcxfg@adi>
<420202D0.7070602@archonet.com>
<opslmno9cpawcxfg@adi>
<42022DA2.3040000@archonet.com>
<opslmpx0u3awcxfg@adi>
I'll repeat myself:
Please CC the mailing list as well as replying to me, so that others
can help too.
Din Adrian wrote:
>
> On Thu, 03 Feb 2005 13:56:50 +0000, Richard Huxton <dev@archonet.com>
> wrote:
>
>> Please CC the mailing list as well as replying to me, so that others
>> can help too.
>>
>>
>>> b) in docs say that after 7.2 seting this to false does'n turn off
>>> the wall ...!? wich option does?
>>
>>
>> The docs don't say that, as far as I can see. It doesn't make sense
>> to turn off the WAL.
>
>
> hmm this is the doc about ...
>
> ' NOTE: Since 7.2, turning fsync off does NOT stop WAL. It does stop
> checkpointing, however. This is a change in the notes that follow Turn
> WAL off (fsync=false) only for a read-only database or one where the
> database can be regenerated from external software. While RAID plus
> UPSes can do a lot to protect your data, turning off fsync means that
> you will be restoring from backup in the event of hardware or power
> failure.'
I don't know what this is, and you don't give a URL, but it DOES NOT
appear to be in the manuals.
You should probably read the sections of the manuals regarding "run-time
configuration" and "write ahead logs". The manuals are quite extensive,
are available online at http://www.postgresql.org/ and also in most
distributions.
This is probably a good place to start.
http://www.postgresql.org/docs/8.0/interactive/runtime-config.html#RUNTIME-CONFIG-WAL> If you turn it off you should have more speed ... !!!???
Basically, as I said in my last email - fsync=true makes sure
transaction details are safely stored on disk. If you turn this off, the
database doesn't have to wait for the data to physically be written to
the disk. But, if power fails then data might be in OS or disk cache and
so lost when you restart the machine.
Please CC the mailing list if you reply to this message.
--
Richard Huxton
Archonet Ltd
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To: pgsql-sql@postgresql.org
Cc: dev@archonet.com, adrian.din@easynet.ro, pgsql-performance@postgresql.org
Subject: Re: Tunning postgresql on linux (fedora core 3)
In-Reply-To: <42023A94.5040904@archonet.com>
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