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

On 2018-09-19 23:26:52 -0400, Tom Lane wrote:
> Andres Freund <andres@anarazel.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