Re: IN list processing performance (yet again)

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От Dave Tenny
Тема Re: IN list processing performance (yet again)
Дата
Msg-id 3ED514A2.8060107@attbi.com
обсуждение исходный текст
Ответ на Re: IN list processing performance (yet again)  (Mario Weilguni <mweilguni@sime.com>)
Список 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 fooorder 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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