Re: Optimizing nested ConvertRowtypeExpr execution

Sorry for the absense.

At Sun, 4 Nov 2018 16:26:12 +0100, Dmitry Dolgov <9erthalion6(at)gmail(dot)com> wrote in <CA+q6zcWMCNNmMQ-csuDf0Pqr1_ESat5-Vcu5uognfS3EaC4Apg(at)mail(dot)gmail(dot)com>
> > On Sun, 4 Nov 2018 at 15:48, Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> wrote:
> >
> > >>>>> "Dmitry" == Dmitry Dolgov <9erthalion6(at)gmail(dot)com> writes:
> >
> > Dmitry> This patch went through the last tree commit fests without any
> > Dmitry> noticeable activity, but cfbot says it still applies and
> > Dmitry> doesn't break any tests. The patch itself is rather small, and
> > Dmitry> I could reproduce ~20% of performance improvements while
> > Dmitry> running the same scripts under pgbench (although not in all
> > Dmitry> cases), but probably we need to find someone to take over it.
> > Dmitry> Does anyone wants to do so, maybe Kyotaro?
> >
> > I'll deal with it.
>
> Thanks!

My last comment was the while() loop does nothing. Ashutosh said
that it is on the model of RelabelType.

I examined the code for T_RelabelType again and it is intending
that the ece_mutator can convert something (specifically only
CollateExpr) to RelableType, then reduce the nested Relabels. So
the order is not wrong in this perspective.

So I don't object to the current patch, but it needs test like
attached.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center