Re: use pg_get_functiondef() in pg_dump

I count myself among those folks (see https://www.postgresql.org/message-id/CADkLM%3DfxfsrHASKk_bY_A4uomJ1Te5MfGgD_rwwQfV8wP68ewg%40mail.gmail.com for discussion of doing DESCRIBE and SHOW CREATE-ish functions either on server side or client side).

I'm all for having this as "just" as set of pg_get_*def functions, because they allow for the results to be used in queries. Granted, the shape of the result set may not be stable, but that's the sort of thing we can warn for the same way we have warnings for changes to pg_stat_activity. At that point any DESCRIBE/SHOW CREATE server side functions essentially become just shells around the pg_get_*def(), with no particular requirement to make those new commands work inside a SELECT.

Would it be totally out of left field to have the functions have an optional "version" parameter, defaulted to null, that would be used to give backwards compatible results if and when we do make a breaking change?