From: | "Luke Lonergan" <llonergan(at)greenplum(dot)com> |
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To: | "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>, pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Good News re count(*) in 8.1 |
Date: | 2006-02-22 17:11:50 |
Message-ID: | C021DB56.1D021%llonergan@greenplum.com |
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Lists: | pgsql-performance |
Kevin,
On 2/22/06 8:57 AM, "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> wrote:
> I hesitate to raise this issue again, but I've noticed something which I
> thought might be worth mentioning. I've never thought the performance
> of count(*) on a table was a significant issue, but I'm prepared to say
> that -- for me, at least -- it is officially and totally a NON-issue.
Cool! Kudos to Tom for implementing the improvements in the executor to
move tuples faster through the pipeline.
We see a CPU limit (yes, another limit) of about 300MB/s now on Opteron 250
processors running on Linux. The filesystem can do 420MB/s sequential scan
in 8k pages, but Postgres count(*) on 8.1.3 can only do about 300MB/s. This
is still a very large improvement over past versions, but we'd always like
to see more...
- Luke
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