Re: A doubt w.r.t WAL

From: Lincoln Yeoh <lyeoh(at)pop(dot)jaring(dot)my>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Shridhar Daithankar <shridhar_daithankar(at)persistent(dot)co(dot)in>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: A doubt w.r.t WAL
Date: 2003-07-22 16:38:53
Message-ID: 5.2.1.1.1.20030723003548.02cd7c88@mbox.jaring.my
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If I'm doing a reasonably sized COPY e.g. a few hundred megabytes, would
WAL segment size and number be relevant? If so any pointers on how I should
tweak stuff?

How about for speeding up many inserts?

At 12:13 AM 7/22/2003 -0400, Tom Lane wrote:

>AFAIR you cannot force the system to have only one WAL segment; it
>*will* make another one when it has to.
>
>Once it has established a checkpoint within the current WAL segment,
>it is able to delete the previous segment, and will do so if you've
>set the WAL parameters that small. I don't really recommend doing
>so however. Creating and deleting WAL segments is expensive, and not
>very productive compared to recycling them. The out-of-the-box
>settings allow the system to recycle three or so WAL segments.
>Unless you're truly desperate for disk space you should not reduce
>the default WAL settings.
>
> regards, tom lane
>
>---------------------------(end of broadcast)---------------------------
>TIP 7: don't forget to increase your free space map settings

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