Thread: 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 1500 Broadway New York, NY 10036 (212) 329-5251 http://www.vmsinfo.com The Leader in Integrated Media Intelligence Solutions
Hi Mladen,
Which attribute in the postgresql.conf file this is set ?
I am running CentOS Linux, PG 8.4
Thanks!
Arvind
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
1500 Broadway
New York, NY 10036
(212) 329-5251
http://www.vmsinfo.com The Leader in Integrated Media Intelligence Solutions
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Which attribute in the postgresql.conf file this is set ?
I am running CentOS Linux, PG 8.4
Thanks!
Arvind
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
1500 Broadway
New York, NY 10036
(212) 329-5251
http://www.vmsinfo.com The Leader in Integrated Media Intelligence Solutions
-- Sent via pgsql-novice mailing list (pgsql-novice@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-novice
D'oh !
Didn't read the post carefully.
Thanks!
Arvind
Didn't read the post carefully.
Thanks!
Arvind
From: William Furnass <will@thearete.co.uk>
To: Arvind Sharma <arvind321@yahoo.com>
Cc: Mladen Gogala <mgogala@vmsinfo.com>; "pgsql-novice@postgresql.org" <pgsql-novice@postgresql.org>
Sent: Wed, September 15, 2010 7:56:07 AM
Subject: Re: [NOVICE] Neat trick
blockdev is a Linux utility for examining block devices (such as
/dev/sda) and for configuring certain aspects of how I/O is performed
on those devices. See http://man.he.net/man8/blockdev.
Will
On 15 September 2010 15:33, Arvind Sharma <arvind321@yahoo.com> wrote:
> Hi Mladen,
>
> Which attribute in the postgresql.conf file this is set ?
>
> I am running CentOS Linux, PG 8.4
>
> Thanks!
> Arvind
>
>
> ________________________________
> 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
> 1500 Broadway
> New York, NY 10036
> (212) 329-5251
> http://www.vmsinfo.com The Leader in Integrated Media Intelligence Solutions
>
>
>
>
> -- Sent via pgsql-novice mailing list (pgsql-novice@postgresql.org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-novice
>
>
blockdev is a Linux utility for examining block devices (such as /dev/sda) and for configuring certain aspects of how I/O is performed on those devices. See http://man.he.net/man8/blockdev. Will On 15 September 2010 15:33, Arvind Sharma <arvind321@yahoo.com> wrote: > Hi Mladen, > > Which attribute in the postgresql.conf file this is set ? > > I am running CentOS Linux, PG 8.4 > > Thanks! > Arvind > > > ________________________________ > 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 > 1500 Broadway > New York, NY 10036 > (212) 329-5251 > http://www.vmsinfo.com The Leader in Integrated Media Intelligence Solutions > > > > > -- Sent via pgsql-novice mailing list (pgsql-novice@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-novice > >
Arvind, this is not a postgresql.conf, this is an OS trick. Your linux has "blockdev" command. Arvind Sharma wrote: > Hi Mladen, > > Which attribute in the postgresql.conf file this is set ? > > I am running CentOS Linux, PG 8.4 > > Thanks! > Arvind > > > ------------------------------------------------------------------------ > *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 > 1500 Broadway > New York, NY 10036 > (212) 329-5251 > http://www.vmsinfo.com The Leader in Integrated Media Intelligence > Solutions > > > > > -- Sent via pgsql-novice mailing list (pgsql-novice@postgresql.org > <mailto:pgsql-novice@postgresql.org>) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-novice > -- Mladen Gogala Sr. Oracle DBA 1500 Broadway New York, NY 10036 (212) 329-5251 http://www.vmsinfo.com The Leader in Integrated Media Intelligence Solutions