Re: pg_standby and build farm - Mailing list pgsql-hackers

From Doug Knight
Subject Re: pg_standby and build farm
Date
Msg-id 1167313540.3933.58.camel@arc-dknightlx.wsicorp.com
Whole thread Raw
In response to Re: pg_standby and build farm  ("Simon Riggs" <simon@2ndquadrant.com>)
Responses Re: pg_standby and build farm
List pgsql-hackers
Thanks for the response, Simon. I'm continuing to use your script, so if there's anything I can help you with
(testing,ideas, etc), just let me know.<br /><br /> Doug<br /><br /> On Thu, 2006-12-28 at 13:40 +0000, Simon Riggs
wrote:<blockquote type="CITE"><pre>
 
<font color="#000000">On Wed, 2006-12-27 at 20:09 +0000, Simon Riggs wrote:</font>

<font color="#000000">> The reason for the -m option was performance. Recovery is I/O-bound,</font>
<font color="#000000">> with 50% of the CPU it does use coming from IsRecordValid() - which is</font>
<font color="#000000">> where the CRC checking takes place. (I can add an option to recover</font>
<font color="#000000">> without CRC checks, if anyone wants it, once I've rejigged the option</font>
<font color="#000000">> parsing for recovery.conf.)</font>

<font color="#000000">Make that 70% of the CPU, for long running recoveries, but the CPU only</font>
<font color="#000000">gets as high as 20% on my tests, so still I/O bound.</font>

<font color="#000000">> Should be able to use hard links, i.e. ln -f -s /archivepath/%f %p</font>
<font color="#000000">> instead. I'll test that tomorrow then issue a new version.</font>

<font color="#000000">The ln works, and helps, but not that much. I'll remove the -m option</font>
<font color="#000000">and replace it with an -l option. Must be careful to use the -f option.</font>

<font color="#000000">The majority of the I/O comes from writing dirty buffers, so enabling</font>
<font color="#000000">the bgwriter during recovery would probably be more helpful.</font>

</pre></blockquote>

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