Hi, On Fri, Jan 21, 2022 at 09:23:34PM +0100, Pavel Stehule wrote: > > I am sending updated patches
I've been looking a bit deeper at the feature and I noticed that there's no locking involved around the session variable usage, and I don't think that's ok. AFAICS any variable used in a session will be cached in the local hash table and will never try to access some catalog or cache, so I don't have any naive scenario that would immediately crash, but this has some other implications that seems debatable. For instance, right now nothing prevents a variable from being dropped while another session is using it. Obviously we can't lock a session variable forever just because a session assigned a value once ages ago, especially outside of the current transaction. But if a session set a variable in the local transaction, I don't think that it's ok to have a subsequent query failing because someone else concurrently dropped the variable. I only backlogged this current thread but I didn't see that being discussed.
