Re: pg_restore dependencies

Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
> We still have a little work to do on dependencies in parallel
> pg_restore. The current test compares the candidate's locking
> dependencies with those of the running jobs, and allows the candidate is
> there isn't a match. That's not a broad enough test. The candidate will
> block if there's a currently running CREATE INDEX command on the table,
> for example, even though that doesn't require an exclusive lock. That's
> not catastrophic, in that the restore doesn't fail, but it's fairly bad
> because it reduces the achievable parallelism. Josh Berkus observed this
> during testing on a very large restore.

Well, we certainly want to be able to run CREATE INDEXes in parallel,
so this would appear to require hard-wiring some conception of shared
versus exclusive lock into pg_restore. I think it might be a bit late
to consider that for 8.4.

regards, tom lane