On 2018-08-22 18:29:58 -0400, Jonathan S. Katz wrote: > > > On Aug 22, 2018, at 2:58 PM, Andreas Joseph Krogh <andr...@visena.com> > > wrote: > > > > På onsdag 22. august 2018 kl. 20:52:05, skrev Andres Freund > > <and...@anarazel.de <mailto:and...@anarazel.de>>: > > On 2018-08-22 19:51:12 +0200, Andreas Joseph Krogh wrote: > > > I thought JITing of prepared queries happended once (in "prepare") > > > > No, it happens when the first JITed function is executed. > > > > > > > so it didn't have to do the JITing every time the query is > > > executed. Isn't the previously generated bytecode usable for > > > subsequent queries? > > > > No, not currently. There's some reasons preventing that (primarily that > > we currently rely on addresses of certain things not to change during > > execution). There's ongoing work to change that, but that's certainly > > not going to be ready for v11. > > > > Greetings, > > > > Andres Freund > > > > > > Ok, thanks for clarifying. > > Per earlier note[1] I was able to reproduce this issue with similar results to > Andreas while running 11 Beta 3. > > jit = on > https://explain.depesz.com/s/vgzD <https://explain.depesz.com/s/vgzD> > > Planning Time: 0.921 ms > JIT: > Functions: 193 > Generation Time: 121.595 ms > Inlining: false > Inlining Time: 0.000 ms > Optimization: false > Optimization Time: 58.045 ms > Emission Time: 1201.100 ms > Execution Time: 1628.017 ms > > jit = off > https://explain.depesz.com/s/AvZM <https://explain.depesz.com/s/AvZM> > > Planning Time: 1.398 ms > Execution Time: 256.473 ms > > I increased the the search range I used in the query by 3x, and got these > numbers: > > jit=on > Planning Time: 0.931 ms > JIT: > Functions: 184 > Generation Time: 126.587 ms > Inlining: true > Inlining Time: 98.865 ms > Optimization: true > Optimization Time: 20518.982 ms > Emission Time: 7270.963 ms > Execution Time: 28772.576 ms > > jit=off > Planning Time: 1.527 ms > Execution Time: 959.160 ms
For the archives sake: This likely largely is the consequence of building with LLVM's expensive assertions enabled, as confirmed by Jonathan over IM. Greetings, Andres Freund
