Re: pgbench questions
[Cc:ed to hackers]
From: nconway@klamath.dyndns.org (Neil Conway)
Subject: pgbench questions
Date: Sat, 13 Jul 2002 00:57:37 -0400
Message-ID: <20020713045736.GA9258@klamath.dyndns.org>
Hi,
I was looking at doing some performance profiling on PostgreSQL, and
I had a few questions on pgbench.(1) Is there a reason you chose to use the TPC-B benchmark rather
than TPC-C or TPC-H, for example? Do you think there might be any
merit in converting pgbench to use TPC-H or AS3AP?
Just easy to implement. Ideally pgbench should be able handle to
several kinds of benchmarks (I don't have time to do that sigh...)
BTW, TPC-H is very different from othe benchmarks. As far as I know,
it focuses on Data Ware House. So TPC-H cannot be a replacement for
TPC-B.
(2) At least in the current CVS version, the code to do a 'CHECKPOINT'
after creating a table has been #ifdef'ed out. Why is that?
That is not after creation of a table, but while creating it, which is
not necessary any more since Tom has fix the growth of WAL logs.
(3) Several people (Rod Taylor, Tom Lane, myself, perhaps others) have
noticed that the results obtained from pgbench can be somewhat
inconsistent (i.e. can vary between runs quite a bit).Have you found this to be the case in your own experience?
Do you have any suggestions on how pgbench can be made more
consistent (either through special benchmarking procedures, or
through a change to pgbench)
I believe it's a common problem with benchmark programs. I think Tom
or Jan has posted a good summary to hackers list showing how to get
a consistent result with pgbench.
--
Tatsuo Ishii
Import Notes
Reply to msg id not found: 20020713045736.GA9258@klamath.dyndns.orgReference msg id not found: 20020713045736.GA9258@klamath.dyndns.org
On Sat, 2002-07-13 at 02:25, Tatsuo Ishii wrote:
(2) At least in the current CVS version, the code to do a 'CHECKPOINT'
after creating a table has been #ifdef'ed out. Why is that?That is not after creation of a table, but while creating it, which is
not necessary any more since Tom has fix the growth of WAL logs.
Tatsou:
Could you or Tom give me some background on what this change was about?
Is this something recent, or would it have been in CVS about a month
ago?
I can't see any reason to force a checkpoint after CREATE TABLE, but it
would be interesting to know why it was done before.
;John Nield
--
J. R. Nield
jrnield@usol.com
J. R. Nield wrote:
On Sat, 2002-07-13 at 02:25, Tatsuo Ishii wrote:
(2) At least in the current CVS version, the code to do a 'CHECKPOINT'
after creating a table has been #ifdef'ed out. Why is that?That is not after creation of a table, but while creating it, which is
not necessary any more since Tom has fix the growth of WAL logs.Tatsou:
Could you or Tom give me some background on what this change was about?
Is this something recent, or would it have been in CVS about a month
ago?I can't see any reason to force a checkpoint after CREATE TABLE, but it
would be interesting to know why it was done before.
7.1.0 had a problem with WAL file growth. This was fixed in 7.1.2 or
7.1.3 so checkpoint is not required anymore.
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 853-3000
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