Re: Is stats update during COPY IN really a good idea?

Bruce Momjian <pgman@candle.pha.pa.us> writes:
> People are using COPY into the same table at the same time? 

Yes --- we had a message from someone who was doing that (and running
into unrelated performance issues) just last week.

> My vote is to update pg_class.  The VACUUM takes much more time than the
> update, and we are only updating the pg_class row, right?

What?  What does VACUUM have to do with this?

The reason this is a significant issue is that the first COPY could be
inside a transaction, in which case the lock will persist until that
transaction commits, which could be awhile.

> Can't we just start a new transaction and update the pg_class row,
> that way we don't have to open it for writing during the copy.

No, we cannot; requiring COPY to happen outside a transaction block is
not acceptable.
        regards, tom lane