[CALCITE-3984] Support exchange operator in RelFieldTrimmer

• Type: Wish
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.23.0
• Assignee: Unassigned
• Reporter: xzh_dz
• Created: 09/May/20 11:47
• Updated: 24/May/20 12:00
• Resolved: 11/May/20 03:50

Description

RelFieldTrimmer does not support trim unused fields in exchange operator now.
Such as below:

final RelBuilder builder = RelBuilder.create(config().build());
    final RelNode root =
        builder.scan("EMP")
            .project(builder.field("EMPNO"), builder.field("ENAME"), builder.field("DEPTNO"))
            .exchange(RelDistributions.hash(Lists.newArrayList(1)))
            .project(builder.field("EMPNO"), builder.field("ENAME"))
            .build();

RelNode root:

LogicalProject(EMPNO=[$0], ENAME=[$1])
  LogicalExchange(distribution=[hash[1]])
    LogicalProject(EMPNO=[$0], ENAME=[$1], DEPTNO=[$7])
      LogicalTableScan(table=[[scott, EMP]])

The right result should be:

LogicalExchange(distribution=[hash[1]])
  LogicalProject(EMPNO=[$0], ENAME=[$1])
    LogicalTableScan(table=[[scott, EMP]])

Issue Links

• links to: https://github.com/apache/calcite/pull/1967