Re: Bug in prepared statement cache invalidation?

On Tue, May 2, 2017 at 5:50 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> Yeah. I think there should be a way to tell a PL to flush any
>> internal caches it is maintaining, some variant of DISCARD. But that
>> would require a bunch of code that nobody's written yet.
>
> That mechanism already exists, so far as the core code is concerned:
> register a syscache inval callback. But you're right, getting plpgsql
> to actually do anything about changes in composite types would require
> a bunch of code that nobody's written yet.

Well, that'd be a way of doing automatic invalidations, not manual
ones. Making DISCARD PROCEDURAL LANGUAGE CRAP work would a different
pile of code.

> If you'll pardon my bashing on a long-deceased horse, this would be
> noticeably easier if we stopped using the PLPGSQL_DTYPE_ROW code
> paths for composite-type variables. That mechanism was really
> designed for cases like "SELECT ... INTO a,b,c" where the row
> contents are fully determined by the function text. It's practically
> impossible to make it cope with dynamic changes; at the very least
> you have to recompile the whole function.

I guess that's also a project in need of some round tuits.

--
Robert Haas
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