On Thu, Sep 6, 2018 at 4:22 PM Michael Paquier <mich...@paquier.xyz> wrote: > > On Wed, Sep 05, 2018 at 09:23:37AM -0700, Andres Freund wrote: > > Well, we kinda do, during some of their own DDL. CF > > AcquireDeletionLock(), RangeVarGetAndCheckCreationNamespace(), and other > > LockDatabaseObject() callers. The > > RangeVarGetAndCheckCreationNamespace() even locks the schema an object > > is created in , which is pretty much what we're discussing here. > > > > I think the problem with the current logic is more that the > > findDependentObjects() scan doesn't use a "dirty" scan, so it doesn't > > ever get to seeing conflicting operations. > > Well, it seems to me that we don't necessarily want to go down to that > for sure on back-branches. What's actually striking me as a very bad > thing is the inconsistent behavior when we need to get a namespace OID > after calling QualifiedNameGetCreationNamespace using a list of defnames > which does not lock the schema the DDL is working on. And this happens > for basically all the object types Jimmy has mentioned. > > For example, when creating a composite type, the namespace lock is taken > through RangeVarGetAndCheckCreationNamespace. If a user tries to create > a root type, then we simply don't lock it, which leads to an > inconsistency of behavior between composite types and root types. In my > opinion the inconsistency of behavior for the same DDL is not logic. > > So I have been looking at that, and finished with the attached, which > actually fixes the set of problems reported. Thoughts?
Hi, I applied to current master and run "make check-world" and everything is ok... I also run some similar tests as Jimmy pointed and using PLpgSQL to execute DDLs and the new consistent behavior is ok. Also I run one session using DROP SCHEMA at end and after COMMIT the session 2 report 'ERROR: schema "testschema" does not exist', so avoiding concerns about lock overhead seems the proposed patch is ok. Regards, -- Fabrízio de Royes Mello Timbira - http://www.timbira.com.br/ PostgreSQL: Consultoria, Desenvolvimento, Suporte 24x7 e Treinamento
