[DRILL-6545] Projection Push down into Lateral Join operator.

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.14.0
• Component/s: Query Planning & Optimization
• Labels: ready-to-commit
• Assignee: Hanumath Rao Maduri
• Reporter: Hanumath Rao Maduri
• Reviewer: Aman Sinha
• Created: 27/Jun/18 13:21
• Updated: 02/Jul/18 06:35
• Resolved: 02/Jul/18 06:35

Description

For the Lateral’s logical and physical plan node, we would need to add an output RowType such that a Projection can be pushed down to Lateral. Currently, Lateral will produce all columns from left and right and it depends on a subsequent Project to eliminate unneeded columns. However, this will blow up the memory use of Lateral since each column from the left will be replicated N times based on N rows coming from UNNEST. We can have a ProjectLateralPushdownRule that pushes only the plain columns onto LATERAL but keeps the expression evalulations as part of the Project above the Lateral.

Issue Links

• is depended upon by: DRILL-5999 Add support for LATERAL join
• links to: GitHub Pull Request #1347