Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/20201#discussion_r163010318
--- Diff:
sql/core/src/main/java/org/apache/spark/sql/sources/v2/reader/Partitioning.java
---
@@ -0,0 +1,46 @@
+/*
+ * 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.spark.sql.sources.v2.reader;
+
+import org.apache.spark.annotation.InterfaceStability;
+
+/**
+ * An interface to represent the output data partitioning for a data
source, which is returned by
+ * {@link SupportsReportPartitioning#outputPartitioning()}. Note that this
should work like a
+ * snapshot. Once created, it should be deterministic and always report
same number of partitions
+ * and same "satisfy" result for a certain distribution.
+ */
[email protected]
+public interface Partitioning {
+
+ /**
+ * Returns the number of partitions/{@link ReadTask}s the data source
outputs.
+ */
+ int numPartitions();
+
+ /**
+ * Returns true if this partitioning can satisfy the given distribution,
which means Spark does
+ * not need to shuffle the output data of this data source for some
certain operations.
+ *
+ * Note that, Spark may add new concrete implementations of {@link
Distribution} in new releases.
+ * This method should be aware of it and always return false for
unrecognized distributions. It's
+ * recommended to check every Spark new release and support new
distributions if possible, to
+ * avoid shuffle at Spark side for more cases.
+ */
+ boolean satisfy(Distribution d);
--- End diff --
`d` -> `distribution`
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