From: PFC <lists@boutiquenumerique.com>
To: 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 17:33:21 +0200
Message-ID: <op.st52tvunth1vuj@localhost> (raw)
In-Reply-To: <59d991c405071907482bb0689b@mail.gmail.com>
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>
<59d991c405071907482bb0689b@mail.gmail.com>
What happens if, say at iteration 6000 (a bit after the mess starts), you
pause it for a few minutes and resume. Will it restart with a plateau like
at the beginning of the test ? or not ?
What if, during this pause, you disconnect and reconnect, or restart the
postmaster, or vacuum, or analyze ?
> 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
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To: pgsql-performance@postgresql.org
Cc: lists@boutiquenumerique.com, petrilli@gmail.com, tgl@sss.pgh.pa.us, vivek@khera.org
Subject: Re: Impact of checkpoint_segments under continual load conditions
In-Reply-To: <op.st52tvunth1vuj@localhost>
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