On Wed, May 11, 2016 at 3:52 AM, Andres Freund <and...@anarazel.de> wrote: > On 2016-05-11 03:20:12 +0300, Ants Aasma wrote: >> On Tue, May 10, 2016 at 7:56 PM, Robert Haas <robertmh...@gmail.com> wrote: >> > On Mon, May 9, 2016 at 8:34 PM, David Rowley >> > <david.row...@2ndquadrant.com> wrote: >> > I don't have any at the moment, but I'm not keen on hundreds of new >> > vector functions that can all have bugs or behavior differences versus >> > the unvectorized versions of the same code. That's a substantial tax >> > on future development. I think it's important to understand what >> > sorts of queries we are targeting here. KaiGai's GPU-acceleration >> > stuff does great on queries with complex WHERE clauses, but most >> > people don't care not only because it's out-of-core but because who >> > actually looks for the records where (a + b) % c > (d + e) * f / g? >> > This seems like it has the same issue. If we can speed up common >> > queries people are actually likely to run, OK, that's interesting. >> >> I have seen pretty complex expressions in the projection and >> aggregation. Couple dozen SUM(CASE WHEN a THEN b*c ELSE MIN(d,e)*f >> END) type of expressions. In critical places had to replace them with >> a C coded function that processed a row at a time to avoid the >> executor dispatch overhead. > > I've seen that as well, but Was it the actual fmgr indirection causing > the overhead, or was it ExecQual/ExecMakeFunctionResultNoSets et al?
I don't remember what the exact profile looked like, but IIRC it was mostly Exec* stuff with advance_aggregates also up there. Regards, Ants Aasma -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers