On Thu, 2011-07-07 at 20:56 -0700, Darren Duncan wrote: > > When you create a temporary table, PostgreSQL needs to add rows in > > pg_class, pg_attribute, and probably other system catalogs. So there are > > writes, which aren't possible in a read-only transaction. Hence the > > error. And no, there is no workaround. > > That sounds like a deficiency to overcome. > > It should be possible for those system catalogs to be virtual, defined like > union views over similar immutable tables for the read-only database plus > mutable in-memory ones for the temporary tables. Ideally, yes, from a logical standpoint there are catalog entries that are only interesting to one backend. But that doesn't mean it's easy to do. Remember that catalog lookups (even though most go through a cache) are a path that is important to performance. Also, more complex catalog interpretations may introduce some extra bootstrapping challenges. > Are there any plans in the works to do this? I don't think so. It sounds like some fairly major work for a comparatively minor benefit. Suggestions welcome, of course, to either make the work look more minor or the benefits look more major ;) Regards, Jeff Davis -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
