[CALCITE-4007] MergeJoin collation check should not be limited to join key's order

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 1.24.0
• Component/s: core
• Assignee: Unassigned
• Reporter: Haisheng Yuan
• Created: 18/May/20 22:44
• Updated: 25/Jul/20 15:00
• Resolved: 08/Jun/20 23:41

Description

Given MergeJoin on foo.a=bar.a and foo.b=bar.b,
The collation check on MergeJoin always require it is sorted by (a,b), but after 1.23.0 calcite can generate MergeJoin on collation of (b,a), or even (a,b,c), (b,a,c), which are all legit. We should relax the check condition.

Issue Links

• blocks: CALCITE-4052 Enable Top-down Optimization