[GitHub] [calcite] ViggoC commented on a diff in pull request #3311: [CALCITE-5732] EnumerableHashJoin and EnumerableMergeJoin on composite key return rows matching condition 'null = null'

Wed, 12 Jul 2023 23:55:27 -0700 


ViggoC commented on code in PR #3311:
URL: https://github.com/apache/calcite/pull/3311#discussion_r1262097516


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core/src/main/java/org/apache/calcite/adapter/enumerable/PhysType.java:
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@@ -117,6 +117,25 @@ Expression fieldReference(Expression expression, int field,
    */
   Expression generateAccessor(List<Integer> fields);
 
+  /** Similar to {@link #generateAccessor(List)}, but if one of the fields is 
<code>null</code>,
+   * it will return <code>null</code>.
+   *
+   * <p>For example:
+   *
+   * <blockquote><pre>
+   * new Function1&lt;Employee, Object[]&gt; {
+   *    public Object[] apply(Employee v1) {
+   *        return v1.&lt;fieldN&gt; == null
+   *            ? null
+   *            : v1.&lt;fieldM&gt; == null
+   *                ? null
+   *                : FlatLists.of(v1.&lt;fieldN&gt;, v1.&lt;fieldM&gt;);
+   *    }
+   * }
+   * }</pre></blockquote>
+   */
+  Expression generateNullableAccessor(List<Integer> fields);

Review Comment:
   Why not modify the original function implement, but create a new function 
interface.
   
   



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