Hi, On Fri, Jul 24, 2020, at 15:32, Scott Ribe wrote: > > On Jul 24, 2020, at 4:26 PM, David Rowley <dgrowleyml@xxxxxxxxx> wrote: > > > > It does not really take into account the cost of jitting. > > That is what I was missing. > > I read about JIT when 12 was pre-release; in re-reading after my post I > see that it does not attempt to estimate JIT cost. And in thinking > about it, I realize that would be next to impossible to anticipate how > expensive LLVM optimizstion was going to be. We certainly can do better than now. > In the case where a set of functions is replicated across partitions, > it would be possible to do them once, then project the cost of the > copies. Probably not - JITing functions separately is more expensive than doing them once... The bigger benefit there is to avoid optimizing functions that are likely to be the same. > Perhaps for PG 14 as better support for the combination of JIT > optimization and highly-partitioned data ;-) If I posted a few patches to test / address some of these issue, could you test them with your schema & querries? Regards, Andres
