From: Sergio Gabriel Rodriguez <sgrodriguez@gmail.com>
To: Rusty Conover <rconover@infogears.com>
Cc: Ulrich <ulrich.mierendorff@gmx.net>
Cc: pgsql-performance@postgresql.org
Subject: Re: Subquery WHERE IN or WHERE EXISTS faster?
Date: Sat, 5 Jul 2008 09:02:18 -0300
Message-ID: <15aa6b3e0807050502u463c336bva783927eed2e7e89@mail.gmail.com> (raw)
In-Reply-To: <B68AFD89-4213-4912-8108-8C41913F45CB@infogears.com>
References: <48665741.2060900@gmx.net>
<29009.1214668423@sss.pgh.pa.us>
<4866B624.1090906@gmx.net>
<B7AEEA21-79C7-481D-BB7B-899002CC2174@infogears.com>
<48688B44.6070407@gmx.net>
<B68AFD89-4213-4912-8108-8C41913F45CB@infogears.com>
Hi Ulrich, do you try with
SELECT p.speed FROM processor p
INNER JOIN users_processors up ON p.id=up.processorid
AND up.userid=1
?
Or your question is only about IN and EXIST?
regards,
Sergio Gabriel Rodriguez
Corrientes - Argentina
http://www.3trex.com.ar
On Mon, Jun 30, 2008 at 4:44 AM, Rusty Conover <rconover@infogears.com> wrote:
>
> On Jun 30, 2008, at 1:29 AM, Ulrich wrote:
>
>> I think it will be fast, because the "IN set", which is the result of
>> "SELECT processorid FROM users_processors WHERE userid=4040", is limited to
>> a maximum of ~500 processors which is not very big. Increasing Postgres' RAM
>> would be difficult for me, because I am only running a very small server
>> with 256MB RAM and the webserver also likes to use some RAM.
>>
>> Does Postgre cache the HASH-Table for later use? For example when the user
>> reloads the website.
>>
>
> No the hash table only lives as long as the query is being executed. If
> you're looking for generic caching, I'd suggest memcached may be able to
> fill your needs.
>
> Cheers,
>
> Rusty
> --
> Rusty Conover
> InfoGears Inc.
> http://www.infogears.com
>
>
>
>
>
>
>
> --
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To: pgsql-performance@postgresql.org
Cc: sgrodriguez@gmail.com, rconover@infogears.com, ulrich.mierendorff@gmx.net
Subject: Re: Subquery WHERE IN or WHERE EXISTS faster?
In-Reply-To: <15aa6b3e0807050502u463c336bva783927eed2e7e89@mail.gmail.com>
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