Re: patch: function xmltable

2017-01-25 22:40 GMT+01:00 Andres Freund <andres@anarazel.de>:

> Hi,
>
> > > > I'll try to explain my motivation. Please, check it and correct me
> if I
> > > am
> > > > wrong. I don't keep on my implementation - just try to implement
> XMLTABLE
> > > > be consistent with another behave and be used all time without any
> > > > surprise.
> > > >
> > > > 1. Any function that produces a content can be used in target list.
> We
> > > > support SRF in target list and in FROM part. Why XMLTABLE should be a
> > > > exception?
> > >
> > > targetlist SRFs were a big mistake. They cause a fair number of
> problems
> > > code-wise. They permeated for a long while into bits of both planner
> and
> > > executor, where they really shouldn't belong. Even after the recent
> > > changes there's a fair amount of uglyness associated with them.  We
> > > can't remove tSRFs for backward compatibility reasons, but that's not
> > > true for XMLTABLE
> > >
> > >
> > >
> > ok
> >
> > I afraid when I cannot to reuse a SRF infrastructure, I have to
> reimplement
> > it partially :( - mainly for usage in "ROWS FROM ()"
>

The TableExpr implementation is based on SRF now. You and Alvaro propose
independent implementation like generic executor node. I am sceptic so
FunctionScan supports reading from generic executor node.

Regards

Pavel


> Huh?
>
> Greetings,
>
> Andres Freund
>