Tom Lane escribió: > Robert Haas <robertmh...@gmail.com> writes: > > IIRC the queue has 4K entries, and IIRC a single DDL > > operation might provoke a couple of sinvals, but I'm thinking that > > somebody would probably have to be creating >1024 temp tables a minute > > to overrun the queue, which is very possible but not necessarily > > common. > > Well, one DDL typically generates multiple messages --- one for each > catalog row added/modified/removed, roughly speaking. When I run the > constant create/drop example Jeff posted, I see the AV launcher getting > a catchup signal every few seconds. I didn't try to determine exactly > how many create/drop cycles that was, but I'm pretty sure it's a lot > less than 1000.
Just creating the sequence for the serial column means 16 pg_attribute tuples. There's also two pg_class entries, one more pg_attribute, two pg_type entries, a bunch of pg_depend entries ... I doubt it's less than 30 catalog tuples, all things considered. Double that for the drop. So for a 4k entry table that needs to get 50% full, that's only ~35 temp table creations like that. I hadn't realized sequences used so many pg_attribute entries. -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
