> On Jul 25, 2020, at 6:21 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>
> It shows if Postgres was compiled with JIT support.
>
> When you run EXPLAIN ANALYZE SELECT ... then you can see info about JIT overhead. If you don't see notices about JIT in EXPLAIN, then JIT was not used.
The presence of "jit = on" in the config file does not indicate whether the running PG was actually compiled with JIT. And I'm not sure whether beyond that, compiling with JIT requires presence of anything outside the PG install.