Hi Ashutosh,
(2019/01/15 13:29), Ashutosh Bapat wrote:
I think, there's something better possible. Two partitioned relations
won't use partition-wise join, if their partition schemes do not match.
Partitioned relations with same partitioning scheme share
PartitionScheme pointer. PartitionScheme structure should get an extra
counter, maintaining a count of number of partitioned relations sharing
that structure. When this counter is 1, that relation is certainly not
going to participate in PWJ and thus need not have all the structure
required by PWJ set up. If we use this counter coupled with
enable_partitionwise_join flag, we can get rid of
consider_partitionwise_join flag altogether, I think.
Interesting!
That flag was introduced to disable PWJs when whole-row Vars are
involved, as you know, so I think we need to first eliminate that
limitation, to remove that flag.
Thanks!
Best regards,
Etsuro Fujita
