From: Gregory Stark <stark@enterprisedb.com>
To: Bill Moran <wmoran@collaborativefusion.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: TB-sized databases
Date: Wed, 28 Nov 2007 13:55:02 +0000
Message-ID: <871waah3ux.fsf@oxford.xeocode.com> (raw)
In-Reply-To: <20071128082716.91bbad9c.wmoran@collaborativefusion.com>
References: <4544e0330711260904g45d893a8ub1731e245aa8fc84@mail.gmail.com>
<474B1407.3090607@laotraesquina.com.ar>
<474B1B8C.1030505@gmail.com>
<4544e0330711271218h56ce4cc3p280a9fefff24583d@mail.gmail.com>
<1196197045.4246.1154.camel@ebony.site>
<474CA2FA.2020201@laotraesquina.com.ar>
<Pine.LNX.4.58.0711281248290.3731@aragorn.flymine.org>
<20071128082716.91bbad9c.wmoran@collaborativefusion.com>
"Bill Moran" <wmoran@collaborativefusion.com> writes:
> In response to Matthew <matthew@flymine.org>:
>
>> On Tue, 27 Nov 2007, Pablo Alcaraz wrote:
>> > it would be nice to do something with selects so we can recover a rowset
>> > on huge tables using a criteria with indexes without fall running a full
>> > scan.
>>
>> You mean: Be able to tell Postgres "Don't ever do a sequential scan of
>> this table. It's silly. I would rather the query failed than have to wait
>> for a sequential scan of the entire table."
>>
>> Yes, that would be really useful, if you have huge tables in your
>> database.
>
> Is there something wrong with:
> set enable_seqscan = off
> ?
This does kind of the opposite of what you would actually want here. What you
want is that if you give it a query which would be best satisfied by a
sequential scan it should throw an error since you've obviously made an error
in the query.
What this does is it forces such a query to use an even *slower* method such
as a large index scan. In cases where there isn't any other method it goes
ahead and does the sequential scan anyways.
--
Gregory Stark
EnterpriseDB http://www.enterprisedb.com
Ask me about EnterpriseDB's PostGIS support!
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To: pgsql-performance@postgresql.org
Cc: stark@enterprisedb.com, wmoran@collaborativefusion.com
Subject: Re: TB-sized databases
In-Reply-To: <871waah3ux.fsf@oxford.xeocode.com>
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