On Thu, Dec 20, 2018 at 4:11 PM Alvaro Herrera <alvhe...@2ndquadrant.com> wrote: > Oh, so maybe this case is already handled by plan invalidation -- I > mean, if we run DDL, the stored plan is thrown away and a new one > recomputed. IOW this was already a solved problem and I didn't need to > spend effort on it. /me slaps own forehead
I'm kinda saying the opposite - I'm not sure that it's safe even with the higher lock levels. If the plan is relying on the same partition descriptor being in effect at plan time as at execution time, that sounds kinda dangerous to me. Lowering the lock level might also make something that was previously safe into something unsafe, because now there's no longer a guarantee that invalidation messages are received soon enough. With AccessExclusiveLock, we'll send invalidation messages before releasing the lock, and other processes will acquire the lock and then AcceptInvalidationMessages(). But with ShareUpdateExclusiveLock the locks can coexist, so now there might be trouble. I think this is an area where we need to do some more investigation. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
