Re: OID/XID allocation (was Re: is PG able to handle a >500 GB Database?)

> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > What about pre-fetching of OID's. Does that still happen for every
> > backend?
>
> Only ones that actually allocate some OIDs, I think.
>
> > What about XID's?
>
> XIDs are wasted on a postmaster restart, but not per-backend, because
> they are cached in shared memory instead of locally. I've been thinking
> about changing the code so that OIDs are allocated in the same fashion.
> That would mean an extra spinlock grab per OID allocation, but so what?
> We grab several spinlocks per row creation already. And we could
> increase the number of OIDs allocated per pg_variable file update,
> which would save some time.

Yes, I think the leak of 50 oids for every backend that asks for an OID
is really a waste. I can see this change buying us a few more years
without oid problems.

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