27 січня 2010 р. 19:01 Matthew Wakeling <matt...@flymine.org> написав:
> On Wed, 27 Jan 2010, Віталій Тимчишин wrote: > >> How about SELECT SUM (case when id > 1200000 and id < 1210000 then 1 end) >> from tbl_tracker; >> > > That is very interesting. > > > * All the functions should be noop for null input >> > > Alas, not true for COUNT(*), AVG(), etc. > > select avg(b), count(b), count(*) from (values (2),(null))a(b) gives (2.0, 1, 2) for me, so AVG is in game. Sure, it won't work for count(*), but optimizer already knows which aggregates are strict and which are not, so no new information is needed. Best regards, Vitalii Tymchyshyn
