On Wed, Apr 18, 2018 at 12:07:18PM +1200, David Rowley wrote: > In PG10 the planner's partition pruning could be disabled by changing > the constraint_exclusion GUC to off. This is still the case for PG11, > but only for UPDATE and DELETE queries. There is currently no way to > disable partition pruning for SELECT. > > Should we allow this?
> 3. No new GUCs / Do nothing.
Maybe this is divergent from the details of the implementation; but, from a user's perspective: why not continue to use constraint_exclusion?
My initial reaction is that we need to fix the bug introduced in v10 - leaving constraint_exclusion working as it has historically and not affect the new-as-of-10 ability to prune (maybe better termed as skip...) partitions known during execution to contain no qualified tuples.