Sahil Takiar created HIVE-16998:
-----------------------------------
Summary: Add config to enable HoS DPP only for map-joins
Key: HIVE-16998
URL: https://issues.apache.org/jira/browse/HIVE-16998
Project: Hive
Issue Type: Sub-task
Components: Logical Optimizer, Spark
Reporter: Sahil Takiar
Assignee: Sahil Takiar
HoS DPP will split a given operator tree in two under the following conditions:
it has detected that the query can benefit from DPP, and the filter is not a
map-join (see SplitOpTreeForDPP).
This can hurt performance if the the non-partitioned side of the join involves
a complex operator tree - e.g. the query {{select count(*) from srcpart where
srcpart.ds in (select max(srcpart.ds) from srcpart union all select
min(srcpart.ds) from srcpart)}} will require running the subquery twice, once
in each Spark job.
Queries with map-joins don't get split into two operator trees and thus don't
suffer from this drawback. Thus, it would be nice to have a config key that
just enables DPP on HoS for map-joins.
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
