On Sun, Dec 28, 2014 at 11:53 PM, Jeff Davis <pg...@j-davis.com> wrote: > On Tue, 2014-04-01 at 13:08 -0400, Tom Lane wrote: >> I think a patch that stood a chance of getting committed would need to >> detect whether the aggregate was being called in simple or grouped >> contexts, and apply different behaviors in the two cases. > > The simple context doesn't seem like a big problem even if we change > things as Tomas suggests: > > "IMNSHO these are the issues we really should fix - by lowering the > initial element count (64->4) and using a single memory context." > > In the simple context, there's only one context regardless, so the only > cost I see is from reducing the initial allocation from 64 to some lower > number. But if we're doubling each time, it won't take long to get > there; and because it's the simple context, we only need to do it once.
Tom (tgl), Is my reasoning above acceptable? The current patch, which I am evaluating for commit, does away with per-group memory contexts (it uses a common context for all groups), and reduces the initial array allocation from 64 to 8 (but preserves doubling behavior). Regards, Jeff Davis -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers