Re: pg_replication_origin_drop API potential race condition

On 2021-Feb-09, Amit Kapila wrote:

> > IIUC, you are suggesting to use lock for the particular origin instead
> > of locking the corresponding catalog table in functions
> > pg_replication_origin_advance and replorigin_drop_by_name.

Right.

> I think it won't be that straightforward as we don't have origin_id.
> So what we instead need to do is first to acquire a lock on
> ReplicationOriginRelationId, get the origin_id, lock the specific
> origin and then re-check if the origin still exists. I feel some
> similar changes might be required in pg_replication_origin_advance.

Hmm, ok.

> Now, we can do this optimization if we want but I am not sure if
> origin_drop would be a frequent enough operation that we add such an
> optimization. For now, I have added a note in the comments so that if
> we find any such use case we can implement such optimization in the
> future. What do you think?

By all means let's get the bug fixed. Then, in another patch, we can
optimize further, if there really is a problem.

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Álvaro Herrera 39°49'30"S 73°17'W
"Siempre hay que alimentar a los dioses, aunque la tierra esté seca" (Orual)