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Re: Significantly larger toast tables on 8.4?

From: "Alex Hunsaker" <badalex(at)gmail(dot)com>
To: "Philip Warner" <pjw(at)rhyme(dot)com(dot)au>
Cc: "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us>, "Gregory Stark" <stark(at)enterprisedb(dot)com>, "Stephen R(dot) van den Berg" <srb(at)cuci(dot)nl>, "Robert Haas" <robertmhaas(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Significantly larger toast tables on 8.4?
Date: 2009-01-04 04:29:02
Message-ID: 34d269d40901032029l336c5819nca12b80c1b5cb109@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Sat, Jan 3, 2009 at 20:47, Philip Warner <pjw(at)rhyme(dot)com(dot)au> wrote:
> Tom Lane wrote:
>> It would be fairly easy, I think, to add some reloption fields that
>> would let these parameters be controlled on a per-table level.
>> Per-column would be much more painful; do we really need that?
>>
>
> Another +1 on the per-table setting. Or a config file setting to disable
> this for the instance.
>
> We have a 200GB DB that is mostly large text (>1MB) that is not searched
> with substr. If we see a blowout in size of even 3x, we will not be able
> to upgrade due to disk space limitations (at least without paying for a
> lot of disks on mirror servers and hot-standy servers).

Well I *really* doubt unless your text is extremely redundant you will
see a large increase if any.  Even if you dont search by substr,
fetching the data is quite could be quite a bit faster.  Depending on
how beefy the cpu's on the machine are.  A quick benchmark here says
by as much 200x! (30tps vs 6000tps).  Thats just a simple select on a
dual 2ghz opteron.

For the record I just imported a production database that sits at
about ~20G right now with *zero* size increase (rounding to the
nearest gigabyte).  That's with basically the exact same schema just
different data.

I don't suppose you could export some random rows and see if you see
any size increase for your data?  My gut says you wont see an
increase.

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Next:From: Philip WarnerDate: 2009-01-04 04:56:57
Subject: Re: Significantly larger toast tables on 8.4?
Previous:From: Alvaro HerreraDate: 2009-01-04 04:01:15
Subject: Re: generic reloptions improvement

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