[ARROW-9838] [Rust] [DataFusion] DefaultPhysicalPlanner should insert explicit MergeExec nodes

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.0.0
• Component/s: Rust, Rust - DataFusion
• Assignee: Andy Grove
• Reporter: Andy Grove
• Created: 23/Aug/20 17:10
• Updated: 26/Sep/20 20:52
• Resolved: 26/Sep/20 20:52

Description

Operators such as GlobalLimitExec, SortExec, and HashAggregateExec (in some cases) require a single input partition. Rather than have these operators perform their own merging of input partitions, the planner should insert explicit MergeExec nodes into the physical plan, when needed.