Re: Query JITing with LLVM ORC

=?UTF-8?Q?Jo=C3=A3o_Paulo_Labegalini_de_Carvalho?= <jaopaulolc@gmail.com> writes:
> Good to know. I compiled from the REL_14_5 tag and did a simple experiment
> to contrast building with and w/o passing --with-llvm.
> I ran the TPC-C benchmark with 1 warehouse, 10 terminals, 20min of ramp-up,
> and 120 of measurement time.
> The number of transactions per minute was about the same with & w/o JITing.
> Is this expected? Should I use a different benchmark to observe a
> performance difference?

TPC-C is mostly short queries, so we aren't likely to choose to use JIT
(and if we did, it'd likely be slower).  You need a long query that will
execute the same expressions over and over for it to make sense to
compile them.  Did you check whether any JIT was happening there?

There are a bunch of issues in this area concerning whether our cost
models are good enough to accurately predict whether JIT is a good
idea.  But single-row fetches and updates are basically never going
to use it, nor should they.

            regards, tom lane