On Mon, Aug 13, 2018 at 12:32 PM, Etsuro Fujita <fujita.ets...@lab.ntt.co.jp> wrote: > One thing I noticed might be an improvement is to skip > build_joinrel_partition_info if the given joinrel will be to have > consider_partitionwise_join=false; in the previous patch, that function > created the joinrel's partition info such as part_scheme and part_rels if > the joinrel is considered as partitioned, independently of the flag > consider_partitionwise_join for it, but if that flag is false, we don't > generate PWJ paths for the joinrel, so we would not need to create that > partition info at all. This would not only avoid unnecessary processing in > that function, but also make unnecessary the changes I made to > try_partitionwise_join, generate_partitionwise_join_paths, > apply_scanjoin_target_to_paths, and create_ordinary_grouping_paths. So I > updated the patch that way. Please find attached an updated version of the > patch.
I guess the question is whether there are (or might be in the future) other dependencies on part_scheme. For example, it looks like partition pruning uses it. I'm not sure whether partition pruning supports a plan like: Append -> Nested Loop -> Seq Scan on p1 -> Index Scan on q1 <repeat the above for p2/q2 etc.> If it doesn't, that's just an implementation restriction; somebody might want to fix things so it works, if it doesn't already. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
