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 |
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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.
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