1 files changed, 53 insertions, 0 deletions
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/planner/common/OrderedRel.java b/exec/java-exec/src/main/java/org/apache/drill/exec/planner/common/OrderedRel.java
new file mode 100644
index 000000000..5f4da7439
--- /dev/null
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/planner/common/OrderedRel.java
@@ -0,0 +1,53 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.drill.exec.planner.common;
+
+import org.apache.calcite.rel.RelCollation;
+import org.apache.calcite.rex.RexNode;
+
+/**
+ * Class implementing OrderedPrel interface guarantees to provide ordered
+ * output on certain columns. TopNPrel and SortPrel base classes which implement
+ * this interface.
+ */
+public interface OrderedRel extends DrillRelNode {
+
+  /**
+   * A method to return ordering columns of the result.
+   * @return Collation order of the output.
+   */
+  RelCollation getCollation();
+
+  /**
+   * Offset value represented in RexNode.
+   * @return offset.
+   */
+  RexNode getOffset();
+
+  /**
+   * Fetch value represented in RexNode.
+   * @return fetch
+   */
+  RexNode getFetch();
+
+  /**
+   * A method to return if this relational node can be dropped during optimization process.
+   * @return true if this node can be dropped, false otherwise.
+   */
+  boolean canBeDropped();
+}