[CALCITE-2997] Avoid pushing down join condition in SqlToRelConverter

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.24.0
• Assignee: Julian Hyde
• Reporter: Jin Xing
• Created: 14/Apr/19 06:07
• Updated: 25/Jul/20 15:00
• Resolved: 01/Jun/20 17:20

Description

In current code, SqlToRelConverter:createJoin is calling RelOptUtil.pushDownJoinConditions for optimization. And we can find below conversion from SqlNode to RelNode:

SqlNode:
select * from A join B on A.x = B.x * 2

RelNode (Logical-Plan):
Join (condition:col0=col1)
|-Project(x as col0)
| |-Scan(A)
|-Project(x * 2 as col1)
  |-Scan(B)

As we can see the logical plan(RelNode) posted above is not the pure reflection of the original SQL String(SqlNode). The optimization is mixed into the phase on which AST is converted to Logical-Plan. Actually optimizing rule of JoinPushExpressionsRule is doing exactly the same kind of thing. Shall we just keep the optimization inside Optimized-Logical-Plan ? I mean shall we avoid calling RelOptUtil.pushDownJoinConditions in SqlToRelConverter:createJoin

I raised this issue because that we are doing something based on the Logical-Plan. And it makes us really confused that the Logical-Plan doesn't corresponds to SqlNode.