Re: BUG #17045: 14 Beta Tighten up allowed names for custom GUC parameters breaks PostgREST

Robert Sosinski <robert.sosinski@reactive.io> writes:
> I would revise my statement to say this change to PostgreSQL 14 would
> significantly break existing PostgREST applications, to the point that they
> would be unable to upgrade to 14.

Fair enough.  I also dug around a bit and noted that the core grammar
explicitly allows SET/SHOW variable names to have any number of
components:

var_name:   ColId                                { $$ = $1; }
            | var_name '.' ColId
                { $$ = psprintf("%s.%s", $1, $3); }
        ;

That dates clear back to commit 3dc37cd8d of 2004-05-26.  While it's
fair to wonder how intentional it was, given that the commit log
message only mentions "qualified name in the form <ID>.<ID>",
nonetheless people have been able to write this --- without any tricks
like double-quotes --- for a mighty long time.  So I now agree that
we shouldn't forbid it.  Done at

https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=2955c2be79b35fa369c83fa3b5f44661cb88afa9

            regards, tom lane