Subject: Re: CPU bound
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From: Royce Ausburn <royce@inomial.com>
In-Reply-To: <4D066D0E.6070405@agliodbs.com>
Date: Tue, 14 Dec 2010 08:03:54 +1100
Cc: pgsql-performance@postgresql.org
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Message-Id: <7F2CF023-C154-4F7F-9373-2470D4553096@inomial.com>
References: <F13DEE85-D114-4761-AD4D-924F1A741ACC@inomial.com>
	<4D066D0E.6070405@agliodbs.com>
To: Josh Berkus <josh@agliodbs.com>,
 Craig Ringer <craig@postnewspapers.com.au>

Thanks guys - interesting. =20


On 14/12/2010, at 5:59 AM, Josh Berkus wrote:

> On 12/12/10 6:43 PM, Royce Ausburn wrote:
>> Hi all,
>>=20
>> I notice that when restoring a DB on a laptop with an SDD, typically =
postgres is maxing out a CPU - even during a COPY.  I wonder, what is =
postgres usually doing with the CPU?  I would have thought the disk =
would usually be the bottleneck in the DB, but occasionally it's not.  =
We're embarking on a new DB server project and it'd be helpful to =
understand where the CPU is likely to be the bottleneck.
>=20
> That's pretty normal; as soon as you get decent disk, especially
> something like an SSD with a RAM cache, you become CPU-bound.  COPY =
does
> a LOT of parsing and data manipulation.  Index building, of course, is
> almost pure CPU if you have a decent amount of RAM available.
>=20
> If you're restoring from a pg_dump file, and have several cores
> available, I suggest using parallel pg_restore.
>=20
>=20
> --=20
>                                  -- Josh Berkus
>                                     PostgreSQL Experts Inc.
>                                     http://www.pgexperts.com
>=20
> --=20
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