[jira] [Created] (CALCITE-4668) RelBuilder.join should only emit a correlate when a correlate variable exists

["James Starr (Jira)" <ji...@apache.org>]

James Starr created CALCITE-4668:
------------------------------------

             Summary: RelBuilder.join should only emit a correlate when a correlate variable exists
                 Key: CALCITE-4668
                 URL: https://issues.apache.org/jira/browse/CALCITE-4668
             Project: Calcite
          Issue Type: Improvement
          Components: core
            Reporter: James Starr


We generate correlated join when no correlate variable is present on the right side.  However, this could be simplified to emit a normal join.

Given:
{code:java}
    final RelNode rel = builder
        .scan("EMP")
        .variable(v)
        .scan("DEPT")
        .join(JoinRelType.LEFT,
            builder.equals(builder.field(2, 0, "SAL"),
                builder.literal(1000)),
            ImmutableSet.of(v.get().id))
        .build();
{code}
Currently the following is emitted:
{code}
LogicalFilter(condition=[=($7, $8)])
  LogicalCorrelate(correlation=[$cor0], joinType=[left], requiredColumns=[{0}])
    LogicalTableScan(table=[[scott, EMP]])
    LogicalFilter(condition=[=($cor0.DEPTNO, $0)])
      LogicalTableScan(table=[[scott, DEPT]])
{code}
After the changes the following will be emitted:
{code}
LogicalJoin(condition=[=($7, $8)], joinType=[left])
  LogicalTableScan(table=[[scott, EMP]])
  LogicalTableScan(table=[[scott, DEPT]])
{code}



--
This message was sent by Atlassian Jira
(v8.3.4#803005)