2010/9/22 Dennis Björklund <d...@zigo.dhs.org>: > In > > http://www.postgresql.org/docs/9.0/static/tutorial-window.html > > it say > > "Although avg will produce the same result no matter what order it > processes the partition's rows in, this is not true of all window > functions. When needed, you can control that order using ORDER BY within > OVER." > > While it's true that avg() produce the same result no matter what order. A > ORDER BY clause will affect what rows are included in the computation and > thus change the result (the default window frame is > RANGE BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW). So one can not in > general add an ORDER BY to the example in the tutorial and get the same > result as without an ORDER BY. > > Maybe we can find some better wording of the above?
Your point is true, but I believe it's still ok because the section is a tutorial for novices. If you start to explain everything here, readers don't want to read it to the end. Regards, -- Hitoshi Harada -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
