PG Doc comments form <nore...@postgresql.org> writes:
> A reader of this section
> https://www.postgresql.org/docs/current/sql-set.html of the documentation
> might be forgiven for thinking that Postgres does not support custom
> variables.
They are, in fact, *not* a supported feature. The only intended use
of non-core GUCs was for extensions' parameters. People have abused the
mechanism to create ad-hoc session variables, but we don't encourage it.
The underlying code won't scale to large numbers of variables, there's
no way to declare properties of such a variable in SQL, etc.
There's been an ongoing effort to create a respectable substitute,
but it still hasn't gotten across the finish line [1].
regards, tom lane
[1] https://commitfest.postgresql.org/39/1608/
