On Thu, Jul 3, 2014 at 11:55:40PM +0200, Andres Freund wrote: > I don't think it's just that simple unfortunately. If pg_class entries > get created that didn't exist on the old server there's a chance for oid > conflicts. Consider > > SELECT binary_upgrade.set_next_heap_pg_class_oid('17094'::pg_catalog.oid); > CREATE TABLE table_without_toast_in_old_server(...); > -- heap oid 17094, toast oid 16384 > > SELECT binary_upgrade.set_next_heap_pg_class_oid('16384'::pg_catalog.oid); > CREATE TABLE another_table(...); > ERROR: could not create file ...: File exists > > I think we even had reports of such a problem.
I had not considered this. I don't remember ever seeing such a report. We have had oid mismatch reports, but we now know the cause of those. > The most robust, but not trivial, approach seems to be to prevent toast > table creation if there wasn't a set_next_toast_pg_class_oid(). Then, > after all relations are created, iterate over all pg_class entries that > possibly need toast tables and recheck if they now might need one. Wow, that is going to be kind of odd in that there really isn't a good way to create toast tables except perhaps add a dummy TEXT column and remove it. There also isn't an easy way to not create a toast table, but also find out that one was needed. I suppose we would have to insert some dummy value in the toast pg_class column and come back later to clean it up. I am wondering what the probability of having a table that didn't need a toast table in the old cluster, and needed one in the new cluster, and there being an oid collision. I think the big question is whether we want to go down that route. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + Everyone has their own god. + -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers