On 3/22/07, Jim Nasby <decibel@xxxxxxxxxxx> wrote:
Is there a safe way to deal with tables being passed into a function, specifically in terms of what schema they're in? I can just blindly accept a text string and hope that it's always evaluated in the correct search_path context, but that doesn't seem so good. OTOH, if I accept an OID, there's no great way to pass that to most of the rest of the system... I can cast the OID to regclass, but that doesn't get me a fully-qualified name. It would be nice if there was a way to convert an OID into a fully- qualified name. I'm working on some partitioning stuff, and I'm currently writing a function that will return the name of a partition given the parent table and what period to partition on (ie: day, month, year, etc). Originally, I thought I'd just accept an OID for the table name, but I can't think of a safe way to look up that tables schema name (because I want to return a fully qualified name). Obviously, I can look in pg_class and pg_namespace, but someone could do a DROP TABLE between when I do that lookup and when I actually use the name. So I thought I'd just do a LOCK TABLE... except I need the table name to do that. Catch-22.
You can select pg_class name in transaction by oid 'for update'. This will block drop table, etc. from other sessions. This will only work if you are the superuser however. merlin
