Re: BUG #15344: pg_proc.proisagg was removed incompatibly inPostgreSQL 11

Hi,

On 2018-08-21 14:23:45 +0000, PG Bug reporting form wrote:
> When comparing the current version (10) [1] and the developer version (11)
> [2] of the pg_proc documentation, then it can be seen that the
> pg_proc.proisagg column was removed backwards incompatibly. The
> documentation states for [1]:

Please note that the pg_catalog.* tables (and views) are *NOT* intended
to backwards compatible between major versions. We change them in ways
backward incompatible all the time.


> While I appreciate that an encoded enumeration is more powerful than a
> simple boolean value, I think it would have been better if this change had
> been done backwards compatibly. For example, there could still be a
> pg_proc.proisagg column that defaults to (prokind = 'a').

When could we have removed that? The few people querying it would've
continued to rely on it until we've removed it, leading to the same
outcry.  And supporting both would've required more code, because we
would have to make sure they're consistent, and raise errors etc if not.

Greetings,

Andres Freund