Re: Neat trick

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From: Mladen Gogala <mgogala@vmsinfo.com>
To: "pgsql-novice@postgresql.org" <pgsql-novice@postgresql.org>
Sent: Tue, September 14, 2010 2:30:28 PM
Subject: [NOVICE] Neat trick

I figured out how to speed up the sequential scans using "blockdev" command. Essentially, this increases the read-ahead on the underlying block device for the file system. It will change the read-ahead value for the entire disk, even if there are several partitions on the disk.  The results are very promising. Unfortunately, I didn't take baseline numbers and measure the effect with precision, but the look of it is that things are much faster with the read-ahead set to 2048 instead of the default 256. The read-ahead is measured in sectors read ahead by the OS. The OS is Red Hat Linux, EL 5.5.

--
Mladen Gogala Sr. Oracle DBA
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New York, NY 10036
(212) 329-5251
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