From: Tom Lane <tgl@sss.pgh.pa.us>
To: mladen.gogala@vmsinfo.com
Cc: david@lang.hm <david@lang.hm>
Cc: Craig Ringer <craig@postnewspapers.com.au>
Cc: Vitalii Tymchyshyn <tivv00@gmail.com>
Cc: pgsql-performance@postgresql.org <pgsql-performance@postgresql.org>
Subject: Re: Slow count(*) again...
Date: Tue, 12 Oct 2010 09:56:30 -0400
Message-ID: <23516.1286891790@sss.pgh.pa.us> (raw)
In-Reply-To: <4CB4542E.5010406@vmsinfo.com>
References: <201010091626.18636.neil.whelchel@gmail.com>
<AANLkTimayTM__hHu9RoiLaNhzfpNY6Vo5y4OkbX_sV=o@mail.gmail.com>
<4CB34D69.6060108@emolecules.com>
<4CB4149D.8030803@gmail.com>
<4CB41902.1020503@postnewspapers.com.au>
<alpine.DEB.2.00.1010120118030.21889@asgard.lang.hm>
<4CB4542E.5010406@vmsinfo.com>
Mladen Gogala <mladen.gogala@vmsinfo.com> writes:
> The number of rows is significantly smaller, but the table contains
> rather significant "text" field which consumes quite a bit of TOAST
> storage and the sizes are comparable. Postgres read through 27GB in 113
> seconds, less than 2 minutes and oracle took 2 minutes 37 seconds to
> read through 35GB. I stand corrected: there is nothing wrong with the
> speed of the Postgres sequential scan.
Um ... the whole point of TOAST is that the data isn't in-line.
So what Postgres was actually reading through was probably quite a
lot less than 27Gb. It's probably hard to make a completely
apples-to-apples comparison because the two databases are so different,
but I don't think this one proves that PG is faster than Oracle.
regards, tom lane
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Subject: Re: Slow count(*) again...
In-Reply-To: <23516.1286891790@sss.pgh.pa.us>
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