| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | mladen(dot)gogala(at)vmsinfo(dot)com |
| Cc: | "david(at)lang(dot)hm" <david(at)lang(dot)hm>, Craig Ringer <craig(at)postnewspapers(dot)com(dot)au>, Vitalii Tymchyshyn <tivv00(at)gmail(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
| Subject: | Re: Slow count(*) again... |
| Date: | 2010-10-12 13:56:30 |
| Message-ID: | 23516.1286891790@sss.pgh.pa.us |
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| Lists: | pgsql-hackers pgsql-performance |
Mladen Gogala <mladen(dot)gogala(at)vmsinfo(dot)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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