Alvaro Herrera <[EMAIL PROTECTED]> writes: > I just noticed a problem, which is why I labeled it a WIP: the current > implementation turns pg_database.datminxid to InvalidTransactionId when > the table that has the minimum relminxid is dropped. The problem is > that this could cause "vacuum starvation" if autovacuum is using > datminxid to decide what database to vacuum, and the minimum Xid table > is being dropped continuously. I had refrained from calculating > pg_database.datminxid each time said table is dropped, because doing it > means scanning pg_class and locking pg_database -- I'm wary of deadlock > problems. Not sure what to do here. (Maybe the answer is to do nothing > -- this is a very low probability scenario anyway. Opinions?)
I'd argue that you should do nothing, ie, dropping a table should never affect datminxid. The proper interpretation of the pg_database columns is that we guarantee that all XID's in the database are *at least* thus- and-so, not that the minimum is exact. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq