Philip Warner <pjw@rhyme.com.au> writes:
> Only slightly; one interpretation of a table lock is that it locks all of
> the data in the table; and a lock on the pg_class row locks the metadata. I
> must admit that I am having a little difficulty thinking of a case where
> the distinction would be useful...
I can't see any value in locking the data without locking the metadata.
Given that, the other way round is sort of moot...
> So where do
> SELECT FOR UPDATE IN ROW SHARE MODE
We don't support that (never heard of it before, in fact)
> and
> LOCK TABLE IN ROW EXCLUSIVE MODE statements.
> fit in?
That one is just a table lock (RowExclusiveLock). All the variants
of LOCK TABLE are table-level locks.
regards, tom lane
