optimising UNION performance
От | Rafal Pietrak |
---|---|
Тема | optimising UNION performance |
Дата | |
Msg-id | 1156753406.20343.22.camel@zorro.isa-geek.com обсуждение исходный текст |
Ответы |
Re: optimising UNION performance
Re: optimising UNION performance |
Список | pgsql-general |
Hi all, Is there a way to speed up the query to my 'grand total' logfile, constructed as a UNION of smaller (specialised) logfiles? Access to log1/log2 is quick (If I'm reading ANALYSE log correctly, it's c.a. 100ms each - and it feels like that, so presumebly I'm reading ANALYSE just OK), but the UNION is quite slow (3.5 sec, which I can confirm - it's the real response time of the server in that case) Again, if I'm reading the ANALYSE correctly (and I'm not really sure of that), it looks like the performence is hit by the sort performed by the UNION. The sort is not really needed in this case and don't really know why it's there (my comlog VIEW definition does not request one - or does it implicitly?). One point not shown in the attachment, is that 'brands' and 'clty' are foreing references. Should foreign reference matter here? Can someone give me a hint on how to write a VIEW, that returns concatenation of both log-tables within a sum of their respective access times (as of current, that would be c.a. 200ms) The ANALYSE is taken from postgres v8.1.4 installed from *.deb on Debian-sid, hosted by 800MHz/512MB Duron machine. It really strickes me, that 20k+30k rows is returned in 3.5sec! -- -R
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