[DRILL-2900] Joins are not getting parallelized in TestTpchDistributed unit tests

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 0.8.0
• Fix Version/s: Future
• Component/s: Query Planning & Optimization
• Assignee: Unassigned
• Reporter: Aman Sinha
• Created: 29/Apr/15 05:19
• Updated: 01/Oct/15 16:38

Description

The suite of unit tests in org.apache.drill.TestTpchDistributed are supposed to have parallel joins, parallel aggregations and sort. In order to force parallelism, the slice_target value is set to 10 (default is 100K). However, it looks like the plans of at least a few queries that I tried (query 03, 05, 14) did not have parallelism for the hash joins. The aggregations and sort do have Exchanges, so they are getting parallelized.

There is a likelihood that many plans have BroadcastExchange on the right input of the join and since the left input of the join is typically a single file we may be dropping the exchange on the right input. This should be fixed.