spark PartitionReaderFactory 源码
spark PartitionReaderFactory 代码
文件路径：/sql/catalyst/src/main/java/org/apache/spark/sql/connector/read/PartitionReaderFactory.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;
import org.apache.spark.sql.catalyst.InternalRow;
import org.apache.spark.sql.vectorized.ColumnarBatch;
/**
* A factory used to create {@link PartitionReader} instances.
* <p>
* If Spark fails to execute any methods in the implementations of this interface or in the returned
* {@link PartitionReader} (by throwing an exception), corresponding Spark task would fail and
* get retried until hitting the maximum retry times.
*
* @since 3.0.0
*/
@Evolving
public interface PartitionReaderFactory extends Serializable {
/**
* Returns a row-based partition reader to read data from the given {@link InputPartition}.
* <p>
* Implementations probably need to cast the input partition to the concrete
* {@link InputPartition} class defined for the data source.
*/
PartitionReader<InternalRow> createReader(InputPartition partition);
/**
* Returns a columnar partition reader to read data from the given {@link InputPartition}.
* <p>
* Implementations probably need to cast the input partition to the concrete
* {@link InputPartition} class defined for the data source.
*/
default PartitionReader<ColumnarBatch> createColumnarReader(InputPartition partition) {
throw new UnsupportedOperationException("Cannot create columnar reader.");
}
/**
* Returns true if the given {@link InputPartition} should be read by Spark in a columnar way.
* This means, implementations must also implement {@link #createColumnarReader(InputPartition)}
* for the input partitions that this method returns true.
* <p>
* As of Spark 2.4, Spark can only read all input partition in a columnar way, or none of them.
* Data source can't mix columnar and row-based partitions. This may be relaxed in future
* versions.
*/
default boolean supportColumnarReads(InputPartition partition) {
return false;
}
}
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