Re: Query with high planning time at version 11.1 compared versions10.5 and 11.0

Robert, Ashutosh, any comments on this?  I'm unfamiliar with the
partitionwise join code.

As the comment says it has to do with the equivalence classes being used during merge append. EC's are used to create pathkeys used for sorting. Creating a sort node which has column on the nullable side of an OUTER join will fail if it doesn't find corresponding equivalence class. You may not notice this if both the partitions being joined are pruned for some reason. Amit's idea to make partition-wise join code do this may work, but will add a similar overhead esp. in N-way partition-wise join once those equivalence classes are added.