Re: Concurrent CREATE TABLE/DROP SCHEMA leaves inconsistent leftovers

On Thu, Nov 10, 2011 at 7:00 AM, Nikhil Sontakke <nikkhils(at)gmail(dot)com> wrote:
> PFA, a patch against git head. We take the AccessShareLock lock on the
> schema in DefineRelation now. Note that we do not want to interlock with
> other concurrent creations in the schema. We only want to interlock with
> deletion activity. So even performance wise this should not be much of an
> overhead in case of concurrent DDL operations to the same schema.

If all you need to do is lock a schema, you can just call
LockDatabaseObject(NamespaceRelationId, namespace_oid, 0,
AccessShareLock); there's no need to fake up an objectaddress just to
take a lock. But I think that's not really all you need to do,
because somebody could drop the namespace between the time that you
decide what OID to lock and the time you acquire the lock. So I think
you need something like what we did in RangeVarGetRelid(). See
attached patch.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
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