Tom Lane <t...@sss.pgh.pa.us> wrote: > Andreas Kretschmer <akretsch...@spamfence.net> writes: > > Tom Lane <t...@sss.pgh.pa.us> wrote: > >> I see no bug here. Your second query asks for a much more complicated > >> computation, it's not surprising it takes longer. > > > But sorry, I disagree. It is the same query with the same result. I can't > > see > > how the queries should return different results. > > In the first query > > select id, avg(value) over (partition by value) from values where id = 50 > order by id; > > the avg() calculations are being done over only rows with id = 50. In > the second query > > select * from (select id, avg(value) over (partition by value) from values > order by id) foo where id = 50; > > they are being done over all rows. In this particular example you > happen to get the same result, but that's just because "avg(foo) over > partition by foo" is a dumb example --- it will necessarily just yield > identically foo. In more realistic computations the results would be > different.
Okay, i believe you now ;-) I will try to find a case with different results ... Thx for your fast help! Andreas -- Really, I'm not out to destroy Microsoft. That will just be a completely unintentional side effect. (Linus Torvalds) "If I was god, I would recompile penguin with --enable-fly." (unknown) Kaufbach, Saxony, Germany, Europe. N 51.05082°, E 13.56889° -- Sent via pgsql-performance mailing list (pgsql-performance@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
