Re: Query is over 2x slower with jit=on

On 2018-09-19 23:26:52 -0400, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > On 2018-09-17 17:50:15 -0400, Tom Lane wrote:
> >> Just to throw a contrarian opinion into this: I find the current EXPLAIN
> >> output for JIT to be insanely verbose already.
>
> > Hm, it'd have been nice to get that feedback a little bit earlier, I did
> > inquire...
>
> > Currently:
>
> > JIT:
> > Functions: 2
> > Generation Time: 0.680 ms
> > Inlining: true
> > Inlining Time: 7.591 ms
> > Optimization: true
> > Optimization Time: 20.522 ms
> > Emission Time: 14.607 ms
>
> Just to clarify, that seems perfectly fine for the "machine readable"
> output formats. I'd just like fewer lines in the "human readable"
> output.

Yea, I do think that's a fair complaint.

> > How about making that:
>
> > JIT:
> > Functions: 2

FWIW, not that I want to do that now, but at some point it might make
sense to sub-divide this into things like number of "expressions",
"tuple deforming", "plans", ... Just mentioning that if somebody wants
to comment on reformatting this as well, if we're tinkering anyway.

> > Options: Inlining, Optimization
> > Times (Total, Generation, Inlining, Optimization, Emission): 43.4 ms, 0.680 ms, 7.591 ms, 20.522 ms, 14.607 ms
>
> > or something similar?
>
> That's going in the right direction. Personally I'd make the last line
> more like
>
> Times: generation 0.680 ms, inlining 7.591 ms, optimization 20.522 ms, emission 14.607 ms, total 43.4 ms

Yea, that's probably easier to read.

> (total at the end seems more natural to me, YMMV).

I kind of think doing it first is best, because that's usually the first
thing one wants to know.

> Also, the "options" format you suggest here seems a bit too biased
> towards binary on/off options --- what happens when there's a
> three-way option? So maybe that line should be like
>
> Options: inlining on, optimization on
>
> though I'm less sure about that part.

I'm pretty certain you're right :). There's already arguments around
making optimization more gradual (akin to O1,2,3).

Greetings,

Andres Freund