On Thu, 29 Jan 2004, Tom Lane wrote:
> > jackdb-# GROUP BY memberid_ HAVING (
> Um, that's not what I had in mind at all. Does GROUP BY actually do
> anything at all here? (You didn't answer me as to whether memberid_
> is a unique identifier or not, but if it is, this GROUP BY is just an
> expensive no-op.)
From your comment I assume that there is no transformation in pg that
detects that the group by columns are unique?
> this is all blue-sky speculation anyway. What I'm actually more
> interested in is your statement that MSSQL can do the original query
> quickly. I find that a bit hard to believe because I don't see any
> relevant optimization techniques.
Getting rid of the group by would not give that kind of speedup? Maybe
mssql manage to rewrite the query like that before executing.
In response to
pgsql-performance by date
|Next:||From: Dennis Bjorklund||Date: 2004-01-30 07:23:14|
|Subject: Re: query optimization question|
|Previous:||From: Shridhar Daithankar||Date: 2004-01-30 07:03:45|
|Subject: Re: On the performance of views|