Re: 7.4 Wishlist
От | Magnus Naeslund(f) |
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Тема | Re: 7.4 Wishlist |
Дата | |
Msg-id | 063201c29a42$316532f0$f80c0a0a@mnd обсуждение исходный текст |
Ответ на | 7.4 Wishlist ("Christopher Kings-Lynne" <chriskl@familyhealth.com.au>) |
Ответы |
Re: 7.4 Wishlist
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Список | pgsql-hackers |
Christopher Kings-Lynne <chriskl@familyhealth.com.au> wrote: >> Mysql is planning on making this work: >> >> SELECT id, @a:=COUNT(*), SUM(sum_col)/@a FROM table_name GROUP BY >> id. >> >> Do we have anything like it (After a discussion with Tom i figure >> no). User variables is nice, especially in these kind of queries. > > Well of course they have to make that work - they don't have > subselects :P > > Chris Yeah, but there is a point about running count(*) one time too many. Say if i would like to get a prettyprinting query like this: SELECT id, @a:=COUNT(*), sum_col::text||'/'@a::text FROM table_name; That would be DAMN expensive doing with a subselect: SELECT id, sum_col||'/'||(select COUNT(*) from tabe_name) FROM table_name; I know this example suck eggs, but you get the point where it hurts, right? Magnus - sorry for the dupe, chris
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