[GitHub] [calcite] danny0405 commented on a change in pull request #2189: [CALCITE-4251] Get the origin column, even if it is derived (xzh)

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danny0405 commented on a change in pull request #2189:
URL: https://github.com/apache/calcite/pull/2189#discussion_r522559504



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File path: core/src/main/java/org/apache/calcite/rel/metadata/RelMetadataQuery.java
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@@ -338,25 +338,23 @@ public Double getPercentageOriginalRows(RelNode rel) {
   }
 
   /**
-   * Determines the origin of a column, provided the column maps to a single
-   * column that isn't derived.
+   * Determines the origin of a column.
    *
    * @see #getColumnOrigins(org.apache.calcite.rel.RelNode, int)
    *
    * @param rel the RelNode of the column
    * @param column the offset of the column whose origin we are trying to
    * determine
    *
-   * @return the origin of a column provided it's a simple column; otherwise,
-   * returns null
+   * @return the origin of a column;
    */
   public RelColumnOrigin getColumnOrigin(RelNode rel, int column) {
     final Set<RelColumnOrigin> origins = getColumnOrigins(rel, column);
     if (origins == null || origins.size() != 1) {
       return null;
     }
     final RelColumnOrigin origin = Iterables.getOnlyElement(origins);
-    return origin.isDerived() ? null : origin;
+    return origin;

Review comment:
       The code that uses this method should also be tweaked, such as the `LoptMultiJoin`.




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