[IMPALA-4270] Planner should disallow queries with mt_dop > 0 that are not executable.

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.6.0, Impala 2.7.0
• Fix Version/s: Impala 2.8.0
• Component/s: Frontend
• Target Version: Impala 2.8.0
• Assignee: Alexander Behm
• Reporter: Alexander Behm
• Created: 10/Oct/16 20:19
• Updated: 17/Oct/16 17:40
• Resolved: 17/Oct/16 17:40

Description

We can currently execute queries with mt_dop > 0 as long as there are no distributed joins in the plan. The planner should detect such unsupported cases and fail queries with an appropriate error message.

For HDFS scans that do not yet have an optimized MT implementation in the backend we should fall back to the old scan node with num_scanner_threads=1.

This change will help to enable some of our tests with mt_dop > 0.