spark HasPartitionKey 源码
spark HasPartitionKey 代码
文件路径：/sql/catalyst/src/main/java/org/apache/spark/sql/connector/read/HasPartitionKey.java
/*
* 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.connector.read;
import org.apache.spark.sql.catalyst.InternalRow;
/**
* A mix-in for input partitions whose records are clustered on the same set of partition keys
* (provided via {@link SupportsReportPartitioning}, see below). Data sources can opt-in to
* implement this interface for the partitions they report to Spark, which will use the
* information to avoid data shuffling in certain scenarios, such as join, aggregate, etc. Note
* that Spark requires ALL input partitions to implement this interface, otherwise it can't take
* advantage of it.
* <p>
* This interface should be used in combination with {@link SupportsReportPartitioning}, which
* allows data sources to report distribution and ordering spec to Spark. In particular, Spark
* expects data sources to report
* {@link org.apache.spark.sql.connector.distributions.ClusteredDistribution} whenever its input
* partitions implement this interface. Spark derives partition keys spec (e.g., column names,
* transforms) from the distribution, and partition values from the input partitions.
* <p>
* It is implementor's responsibility to ensure that when an input partition implements this
* interface, its records all have the same value for the partition keys. Spark doesn't check
* this property.
*
* @see org.apache.spark.sql.connector.read.SupportsReportPartitioning
* @see org.apache.spark.sql.connector.read.partitioning.Partitioning
* @since 3.3.0
*/
public interface HasPartitionKey extends InputPartition {
/**
* Returns the value of the partition key(s) associated to this partition. An input partition
* implementing this interface needs to ensure that all its records have the same value for the
* partition keys. Note that the value is after partition transform has been applied, if there
* is any.
*/
InternalRow partitionKey();
}
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