Re: pg_get_domaindef

Andrew Dunstan <andrew@dunslane.net> writes:
> FAST PostgreSQL wrote:
>> Please find attached the patch with modifications

> are you proposing to implement the other functions in this TODO item
> (pg_get_acldef(), pg_get_typedefault(), pg_get_attrdef(),
> pg_get_tabledef(), pg_get_functiondef() ) ?

I haven't entirely understood the use case for any of these.  It's not
pg_dump, for a number of reasons: one being that pg_dump still has to
support older backend versions, and another being that every time we
let backend SnapshotNow functions get involved, we take another hit to
pg_dump's claim to produce a consistent MVCC snapshot.

But my real objection is: do we really want to support duplicative code
in both pg_dump and the backend?  Updating pg_dump is already a major
PITA whenever one adds a new feature; doubling that work isn't
attractive.  (And it'd be double, not just a copy-and-paste, because of
the large difference in the operating environment.)  So I want to hear a
seriously convincing use-case that will justify the maintenance load we
are setting up for ourselves.  "Somebody might want this" is not
adequate.

Perhaps a better area of work would be the often-proposed refactoring of
pg_dump into a library and driver program, wherein the library could
expose individual functions such as "fetch the SQL definition of this
object".  Unfortunately, that'll be a huge project with no payoff until
the end...

            regards, tom lane