spark InputPartition 源码
spark InputPartition 代码
文件路径：/sql/catalyst/src/main/java/org/apache/spark/sql/connector/read/InputPartition.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 java.io.Serializable;
import org.apache.spark.annotation.Evolving;
/**
* A serializable representation of an input partition returned by
* {@link Batch#planInputPartitions()} and the corresponding ones in streaming .
* <p>
* Note that {@link InputPartition} will be serialized and sent to executors, then
* {@link PartitionReader} will be created by
* {@link PartitionReaderFactory#createReader(InputPartition)} or
* {@link PartitionReaderFactory#createColumnarReader(InputPartition)} on executors to do
* the actual reading. So {@link InputPartition} must be serializable while {@link PartitionReader}
* doesn't need to be.
*
* @since 3.0.0
*/
@Evolving
public interface InputPartition extends Serializable {
/**
* The preferred locations where the input partition reader returned by this partition can run
* faster, but Spark does not guarantee to run the input partition reader on these locations.
* The implementations should make sure that it can be run on any location.
* The location is a string representing the host name.
* <p>
* Note that if a host name cannot be recognized by Spark, it will be ignored as it was not in
* the returned locations. The default return value is empty string array, which means this
* input partition's reader has no location preference.
* <p>
* If this method fails (by throwing an exception), the action will fail and no Spark job will be
* submitted.
*/
default String[] preferredLocations() {
return new String[0];
}
}
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