[GitHub] [calcite] julianhyde commented on a change in pull request #1614: [CALCITE-3546] Improve EnumerableDefaults nested loop join

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julianhyde commented on a change in pull request #1614: [CALCITE-3546] Improve EnumerableDefaults nested loop join
URL: https://github.com/apache/calcite/pull/1614#discussion_r352916519
 
 

 ##########
 File path: linq4j/src/main/java/org/apache/calcite/linq4j/EnumerableDefaults.java
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 @@ -1803,7 +1803,21 @@ private boolean innerHasNext() {
       final Predicate2<TSource, TInner> predicate,
       Function2<TSource, TInner, TResult> resultSelector,
       final JoinType joinType) {
-    // Building the result as a list is easy but hogs memory. We should iterate.
+    if (!joinType.generatesNullsOnLeft()) {
+      return nestedLoopJoinOptimized(outer, inner, predicate, resultSelector, joinType);
+    }
+    return nestedLoopJoinAsList(outer, inner, predicate, resultSelector, joinType);
+  }
+
+  /**
+   * Implementation of nested loop join that builds the complete result as a list
+   * and then returns it. This is an easy-to-implement solution, but hogs memory.
+   */
+  private static <TSource, TInner, TResult> Enumerable<TResult> nestedLoopJoinAsList(
+      final Enumerable<TSource> outer, final Enumerable<TInner> inner,
+      final Predicate2<TSource, TInner> predicate,
+      Function2<TSource, TInner, TResult> resultSelector,
+      final JoinType joinType) {
 
 Review comment:
   By the way, {{class EnumerableDefaults}} exists because a java before JDK 8 did not allow default implementations of interface methods.
   
   Now that has changed we could consider removing {{EnumerableDefaults}}.

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