[GitHub] [calcite] hsyuan commented on a change in pull request #1496: [CALCITE-3400] Implement left/right/semi/anti/full join in Interpreter

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hsyuan commented on a change in pull request #1496: [CALCITE-3400] Implement left/right/semi/anti/full join in Interpreter
URL: https://github.com/apache/calcite/pull/1496#discussion_r341899066
 
 

 ##########
 File path: core/src/main/java/org/apache/calcite/interpreter/JoinNode.java
 ##########
 @@ -47,28 +50,121 @@ public JoinNode(Compiler compiler, Join rel) {
   }
 
   public void run() throws InterruptedException {
-    List<Row> rightList = null;
-    final int leftCount = rel.getLeft().getRowType().getFieldCount();
-    final int rightCount = rel.getRight().getRowType().getFieldCount();
-    context.values = new Object[rel.getRowType().getFieldCount()];
-    Row left;
-    Row right;
-    while ((left = leftSource.receive()) != null) {
-      System.arraycopy(left.getValues(), 0, context.values, 0, leftCount);
-      if (rightList == null) {
-        rightList = new ArrayList<>();
-        while ((right = rightSource.receive()) != null) {
-          rightList.add(right);
+
+    final int fieldCount = rel.getLeft().getRowType().getFieldCount()
+        + rel.getRight().getRowType().getFieldCount();
+    context.values = new Object[fieldCount];
+
+    // source for the outer relation of nested loop
+    Source outerSource = leftSource;
+    // source for the inner relation of nested loop
+    Source innerSource = rightSource;
+    if (rel.getJoinType() == JoinRelType.RIGHT) {
+      outerSource = rightSource;
+      innerSource = leftSource;
+    }
+
+    // row from outer source
+    Row outerRow = null;
+    // rows from inner source
+    List<Row> innerRows = null;
+    Set<Row> matchRowSet = new HashSet<>();
+    while ((outerRow = outerSource.receive()) != null) {
+      if (innerRows == null) {
+        innerRows = new ArrayList<Row>();
+        Row innerRow = null;
+        while ((innerRow = innerSource.receive()) != null) {
+          innerRows.add(innerRow);
         }
       }
-      for (Row right2 : rightList) {
-        System.arraycopy(right2.getValues(), 0, context.values, leftCount,
-            rightCount);
-        final Boolean execute = (Boolean) condition.execute(context);
-        if (execute != null && execute) {
+      matchRowSet.addAll(doJoin(outerRow, innerRows, rel.getJoinType()));
+    }
+    if (rel.getJoinType() == JoinRelType.FULL) {
+      // send un-match rows for full join on right source
+      List<Row> empty = new ArrayList<>();
+      for (Row row: innerRows) {
+        if (matchRowSet.contains(row)) {
+          continue;
+        }
+        doSend(row, empty, JoinRelType.RIGHT);
+      }
+    }
+  }
+
+  /**
+   * Execution of the join action, returns the matched rows for the outer source row.
+   */
+  private List<Row> doJoin(Row outerRow, List<Row> innerRows,
+      JoinRelType joinRelType) throws InterruptedException {
+    boolean outerRowOnLeft = joinRelType != JoinRelType.RIGHT;
+    copyToContext(outerRow, outerRowOnLeft);
+    List<Row> matchInnerRows = new ArrayList<>();
+    for (Row innerRow: innerRows) {
+      copyToContext(innerRow, !outerRowOnLeft);
+      final Boolean execute = (Boolean) condition.execute(context);
+      if (execute != null && execute) {
+        matchInnerRows.add(innerRow);
+      }
+    }
+    doSend(outerRow, matchInnerRows, joinRelType);
+    return ImmutableList.copyOf(matchInnerRows);
 
 Review comment:
   Do wen need ImmutableList copy? matchRowSet.addAll() will copy them again, right?

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