[HIVE-8700] Replace ReduceSink to HashTableSink (or equi.) for small tables [Spark Branch]

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.1.0
• Component/s: Spark
• Assignee: Suhas Satish
• Reporter: Xuefu Zhang
• Created: 02/Nov/14 15:23
• Updated: 29/May/15 02:29
• Resolved: 07/Nov/14 08:52

Description

With HIVE-8616 enabled, the new plan has ReduceSinkOperator for the small tables. For example, the follow represents the operator plan for the small table dec1 derived from query

explain select /*+ MAPJOIN(dec)*/ * from dec join dec1 on dec.value=dec1.d;

        Map 2 
            Map Operator Tree:
                TableScan
                  alias: dec1
                  Statistics: Num rows: 0 Data size: 107 Basic stats: PARTIAL Column stats: NONE
                  Filter Operator
                    predicate: d is not null (type: boolean)
                    Statistics: Num rows: 0 Data size: 0 Basic stats: NONE Column stats: NONE
                    Reduce Output Operator
                      key expressions: d (type: decimal(5,2))
                      sort order: +
                      Map-reduce partition columns: d (type: decimal(5,2))
                      Statistics: Num rows: 0 Data size: 0 Basic stats: NONE Column stats: NONE
                      value expressions: i (type: int)

With the new design for broadcasting small tables, we need to convert the ReduceSinkOperator with HashTableSinkOperator or equivalent in the new plan.