On Mon, Jun 29, 2020 at 10:39 AM David Rowley <dgrowle...@gmail.com> wrote: > > On Sat, 27 Jun 2020 at 00:36, Amit Langote <amitlangot...@gmail.com> wrote: > > 2. ExecCheckRTPerms(): checks permissions of *all* partitions before > > executing the plan tree, but maybe it's okay to check only the ones > > that will be accessed > > I don't think it needs to be quite as complex as that. > expand_single_inheritance_child will set the > RangeTblEntry.requiredPerms to 0, so we never need to check > permissions on a partition. The overhead of permission checking when > there are many partitions is just down to the fact that > ExecCheckRTPerms() loops over the entire rangetable and calls > ExecCheckRTEPerms for each one. ExecCheckRTEPerms() does have very > little work to do when requiredPerms is 0, but the loop itself and the > function call overhead show up when you remove the other bottlenecks.
I had forgotten that we set requiredPerms to 0 for the inheritance child tables. > I have a patch somewhere that just had the planner add the RTindexes > with a non-zero requiredPerms and set that in the plan so that > ExecCheckRTPerms could just look at the ones that actually needed > something checked. There's a slight disadvantage there that for > queries to non-partitioned tables that we need to build a Bitmapset > that has all items from the rangetable. That's likely a small > overhead, but not free, so perhaps there is a better way. I can't think of anything for this that doesn't involve having one more list of RTEs or bitmapset of RT indexes in PlannedStmt. -- Amit Langote EnterpriseDB: http://www.enterprisedb.com
