To: "Richard Huxton" <dev@archonet.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: [PERFORM] Tunning postgresql on linux (fedora core 3)
References: <opsll8h2shawcxfg@adi> <420202D0.7070602@archonet.com>
	<opslmno9cpawcxfg@adi> <42022DA2.3040000@archonet.com>
	<opslmpx0u3awcxfg@adi> <42023A94.5040904@archonet.com>
Message-ID: <opslmr5qxxawcxfg@adi>
Date: Thu, 03 Feb 2005 18:59:40 +0200
From: Din Adrian <adrian.din@easynet.ro>
Organization: Om Computer & SoftWare
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sorry about cc ...
this is the site:
http://www.varlena.com/varlena/GeneralBits/Tidbits/annotated_conf_e.html
but I gues is not right ... hmm

Adrian Din


On Thu, 03 Feb 2005 14:52:04 +0000, Richard Huxton <dev@archonet.com>  
wrote:

> 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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