[CALCITE-4784] Ensure Correlate#requiredColumns is subset of columns in left relation

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.28.0
• Component/s: core
• Labels: pull-request-available
• Assignee: Stamatis Zampetakis
• Reporter: Stamatis Zampetakis
• Created: 17/Sep/21 14:26
• Updated: 20/Oct/21 05:24
• Resolved: 20/Sep/21 11:03

Description

The Correlate expression has among others a field (requiredColumns for representing the set of columns that are used by the correlation.

public abstract class Correlate extends BiRel {
  protected final CorrelationId correlationId;
  protected final ImmutableBitSet requiredColumns;
  protected final JoinRelType joinType;

  /**
   * Returns the required columns in left relation required for the correlation
   * in the right.
   *
   * @return columns in left relation required for the correlation in the right
   */
  public ImmutableBitSet getRequiredColumns() {
    return requiredColumns;
  }

As the javadoc indicates (implicitly) these columns must be a subset of the columns of the left relation. This is currently not enforced when creating a correlation which can lead to invalid plans and runtime failures which are hard to investigate.

I propose to introduce an additional check inside Correlate#isValid method for enforcing that required columns are valid.

Issue Links

• links to: GitHub Pull Request #2525