Tom Lane wrote:
> Greg Stark <gsstark@mit.edu> writes:
> > On Fri, Oct 16, 2009 at 12:26 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> >> However, if the columnref looks like "x.y" where x happens to
> >> match some table in the database (and not in the query) that doesn't
> >> have a column y, the implicit-RTE code will have already modified the
> >> querytree before finding out that column y doesn't exist.
>
> > Hm, so if you do nothing then really the only thing that doesn't work
> > is if you have add_missing_from then plpgsql record variables wouldn't
> > work when you tried to reference their columns?
>
> "Do nothing" isn't the right phrase here --- it would take a great deal
> of work and ugly, hard-to-maintain code to get it to work even that badly.
> The code paths in transformColumnRef are fairly messy already :-(.
> Getting rid of add_missing_from would definitely make it easier to
> refactor to support hooks for external variable sources.
>
> The approach I had been thinking about proposing, before David piped up
> with his modest proposal, was to have external variables take precedence
> over implicit RTEs --- ie, we'd call the hook *before* trying the
> add_missing_from case. But that seems pretty weird, and it'd still be
> messy to program. What it would mainly accomplish is to avoid the extra
> lock hazard.
Sounds like a good reason to remove add_missing_from in 8.5.
-- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB
http://enterprisedb.com
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