On 3/9/18 15:56, Andres Freund wrote: > On 2018-03-09 15:28:19 -0500, Peter Eisentraut wrote: >> On 3/6/18 15:16, Andres Freund wrote: >>> 2) Don't load the JIT provider until fully needed. Right now >>> jit_compile_expr() will load the jit provider even if not really >>> needed. We should probably move the first two return blocks in >>> llvm_compile_expr() into jit_compile_expr(), to avoid that. >> >> I see that you have implemented that, but it doesn't seem to have helped >> with my make installcheck times. > > What's the exact comparison you're looking at?
I'm just running `time make installcheck` with default settings, as described in my message from March 6. > I think that's largely that unnecessary trivial queries get JITed and > optimized, because the stats are entirely completely off. Right. I instrumented this a bit, and there are indeed two handfuls of queries that exceed the default JIT thresholds, as well as a few that trigger JIT because they disable some enable_* planner setting, as previously discussed. Should we throw in some ANALYZEs to avoid this? If I set jit_expressions = off, then the timings match again. It's perhaps a bit confusing that some of the jit_* settings take effect at plan time and some at execution time. At the moment, this mainly affects me reading the code ;-), but it would also have some effect on prepared statements and such. Also, jit_tuple_deforming is apparently used only when jit_expressions is on. So, we should work toward more clarity on all these different settings, what they are useful for, when to set them, how they interact. -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
