[CALCITE-3977] RelDecorrelator does not resolve correlation variable with field accesses

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 1.22.0
• Component/s: core
• Assignee: Unassigned
• Reporter: Thomas Rebele
• Created: 07/May/20 14:51
• Updated: 18/May/20 12:43

Description

The RelCorrelator seems to have problems with some plans that contain a field access (probably a RexFieldAccess, but I haven't looked further into it). In this ticket there's a filter on $cor0.birthPlace.city.

Here the complete plan:

before decorrelate
LogicalCorrelate(correlation=[$cor0], joinType=[left], requiredColumns=[{}])
  LogicalTableScan(table=[[bookstore, authors]])
  LogicalFilter(condition=[=('Munich', $cor0.birthPlace.city)])
    LogicalTableScan(table=[[bookstore, authors]])

after decorrelate
LogicalJoin(condition=[=($2, $8)], joinType=[left])
  LogicalTableScan(table=[[bookstore, authors]])
  LogicalJoin(condition=[true], joinType=[inner])
    LogicalFilter(condition=[=('Munich', $cor0.birthPlace.city)])
      LogicalTableScan(table=[[bookstore, authors]])
    LogicalAggregate(group=[{0}])
      LogicalProject(birthPlace=[$2])
        LogicalTableScan(table=[[bookstore, authors]])

There seem to be two problems:

• The LogicalCorrelate has been removed, but the $cor0.birthPlace.city is still in the filter condition.
• The inner join does not seem to be necessary. If it is, could somebody explain, why?

Issue Links

• is related to: CALCITE-3978 RelDecorrelator on a plan with field accesses does not update field indices when adding a projection