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From: Christopher Petrilli <petrilli@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Vivek Khera <vivek@khera.org>
Cc: pgsql-performance@postgresql.org
Subject: Re: Impact of checkpoint_segments under continual load conditions
Date: Tue, 19 Jul 2005 10:48:42 -0400
Message-ID: <59d991c405071907482bb0689b@mail.gmail.com> (raw)
In-Reply-To: <16794.1121718743@sss.pgh.pa.us>
References: <59d991c4050717100874c08a86@mail.gmail.com>
	<A50B8A1F-71A1-4F63-A5F4-1AA58F89557D@khera.org>
	<59d991c405071811457ccdd3f1@mail.gmail.com>
	<16394.1121715156@sss.pgh.pa.us>
	<59d991c405071812342e290f57@mail.gmail.com>
	<16794.1121718743@sss.pgh.pa.us>

On 7/18/05, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > The table has 15 columns, 5 indexes (character, inet and timestamp).
> > No foreign keys. The only other thing running on the machine was the
> > application actually DOING the benchmarking, written in Python
> > (psycopg), but it was, according to top, using less than 1% of the
> > CPU.  It was just talking through a pipe to a psql prompt to do the
> > COPY.
> 
> Sounds pretty plain-vanilla all right.
> 
> Are you in a position to try the same benchmark against CVS tip?
> (The nightly snapshot tarball would be plenty close enough.)  I'm
> just wondering if the old bgwriter behavior of locking down the
> bufmgr while it examined the ARC/2Q data structures is causing this...

Tom,

It looks like the CVS HEAD is definately "better," but not by a huge
amount.  The only difference is I wasn't run autovacuum in the
background (default settings), but I don't think this explains it. 
Here's a graph of the differences and density of behavior:

http://blog.amber.org/diagrams/pgsql_copy_803_cvs.png

I can provide the raw data.  Each COPY was 500 rows.  Note that fsync
is turned off here.  Maybe it'd be more stable with it turned on?

Chris
-- 
| Christopher Petrilli
| petrilli@gmail.com



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