Re: IN list processing performance (yet again)

From: Dave Tenny <tenny(at)attbi(dot)com>
To: Mario Weilguni <mweilguni(at)sime(dot)com>
Cc: Andreas Pflug <Andreas(dot)Pflug(at)web(dot)de>, pgsql-performance(at)postgresql(dot)org
Subject: Re: IN list processing performance (yet again)
Date: 2003-05-28 19:57:22
Message-ID: 3ED514A2.8060107@attbi.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-performance

Mario Weilguni wrote:

>>I'm reminded to relay to the PostgreSQL devos that I might be able to do
>>more in the join or subquery department if
>>PostgreSQL had better performing MAX functions and a FIRST function for
>>selecting rows from groups.
>>("Performing" being the operative word here, since the extensible
>>architecture of PostgreSQL currently makes for poorly
>>performing MAX capabilities and presumably similar user defined
>>aggregate functions).
>>
>>
>
>MIN/MAX is almost in every case replaceable:
>select bar
> from foo
> order by bar limit 1;
>
>instead of
>select max(bar) from foo;
>
>
Yup, been there, done that, but thanks, it's a good tidbit for the
postgresql unaware.

There are some places however where it doesn't work well in query logic,
though I don't have an example off the top of my head
since I've worked around it in all my queries.

In response to

Browse pgsql-performance by date

  From Date Subject
Next Message Dave Tenny 2003-05-28 20:01:34 Re: IN list processing performance (yet again)
Previous Message Bruno Wolff III 2003-05-28 18:41:50 Re: IN list processing performance (yet again)