Re: Subquery WHERE IN or WHERE EXISTS faster?

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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@xxxxxxxxxxxxx> 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
>
>
>
>
>
>
>
> --
> Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-performance
>


[Postgresql General]     [Postgresql PHP]     [PHP Users]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Yosemite]

  Powered by Linux