On Sun, 26 Jul 2020 at 02:54, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> David Rowley <dgrowleyml@gmail.com> writes:
> > ... nested at the bottom level join, about 6 joins deep. The lack of
> > any row being found results in upper level joins not having to do
> > anything, and the majority of the plan is (never executed).
>
> On re-reading this, that last point struck me forcibly. If most of
> the plan never gets executed, could we avoid compiling it? That is,
> maybe JIT isn't JIT enough, and we should make compilation happen
> at first use of an expression not during executor startup.
That's interesting. But it would introduce an additional per
evaluation cost of checking if we're doing the first execution.
David