Re: improve performance of pg_dump with many sequences

On Tue, Jul 16, 2024 at 10:23:08PM -0500, Nathan Bossart wrote:
> On Wed, Jul 17, 2024 at 11:30:04AM +0900, Michael Paquier wrote:
>> Yeah, I have bumped on the same issue. In the long term, I also think
>> that we'd better have pg_sequence_last_value() return a row with
>> is_called and the value scanned. As you say, it won't help except
>> when upgrading from versions of Postgres that are at least to v18,
>> assuming that this change gets in the tree, but that would be much
>> better in the long term and time flies fast.
>
> AFAICT pg_sequence_last_value() is basically an undocumented internal
> function only really intended for use by the pg_sequences system view, so
> changing the function like this for v18 might not be out of the question.
> Otherwise, I think we'd have to create a strikingly similar function with
> slightly different behavior, which would be a bizarre place to end up.

On second thought, I worry that this change might needlessly complicate the
pg_sequences system view. Maybe we should just add a
pg_sequence_get_tuple() function that returns everything in
FormData_pg_sequence_data for a given sequence OID...

--
nathan