[GitHub] [calcite] yanlin-Lynn commented on a change in pull request #2163: [CALCITE-4273] Support get expression lineage for Calc

[GitBox <gi...@apache.org>]

yanlin-Lynn commented on a change in pull request #2163:
URL: https://github.com/apache/calcite/pull/2163#discussion_r516402810



##########
File path: core/src/main/java/org/apache/calcite/rel/metadata/RelMdExpressionLineage.java
##########
@@ -407,6 +409,35 @@ protected RelMdExpressionLineage() {}
     return mq.getExpressionLineage(rel.getInput(), outputExpression);
   }
 
+  /**
+   * Expression lineage from Calc.
+   */
+  public Set<RexNode> getExpressionLineage(Calc calc,
+      RelMetadataQuery mq, RexNode outputExpression) {
+    final RelNode input = calc.getInput();
+    final RexBuilder rexBuilder = calc.getCluster().getRexBuilder();
+    // Extract input fields referenced by expression
+    final ImmutableBitSet inputFieldsUsed = extractInputRefs(outputExpression);
+
+    // Infer column origin expressions for given references
+    final Map<RexInputRef, Set<RexNode>> mapping = new LinkedHashMap<>();
+    Pair<ImmutableList<RexNode>, ImmutableList<RexNode>> calcFilterAndProjects =
+        calc.getProgram().split();

Review comment:
       OK, I'll update 




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