org.apache.spark.sql.sources.v2.ReadSupportWithSchema Maven / Gradle / Ivy
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* 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,
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package org.apache.spark.sql.sources.v2;
import org.apache.spark.annotation.InterfaceStability;
import org.apache.spark.sql.sources.v2.reader.DataSourceReader;
import org.apache.spark.sql.types.StructType;
/**
* A mix-in interface for {@link DataSourceV2}. Data sources can implement this interface to
* provide data reading ability and scan the data from the data source.
*
* This is a variant of {@link ReadSupport} that accepts user-specified schema when reading data.
* A data source can implement both {@link ReadSupport} and {@link ReadSupportWithSchema} if it
* supports both schema inference and user-specified schema.
*/
@InterfaceStability.Evolving
public interface ReadSupportWithSchema extends DataSourceV2 {
/**
* Create a {@link DataSourceReader} to scan the data from this data source.
*
* If this method fails (by throwing an exception), the action would fail and no Spark job was
* submitted.
*
* @param schema the full schema of this data source reader. Full schema usually maps to the
* physical schema of the underlying storage of this data source reader, e.g.
* CSV files, JSON files, etc, while this reader may not read data with full
* schema, as column pruning or other optimizations may happen.
* @param options the options for the returned data source reader, which is an immutable
* case-insensitive string-to-string map.
*/
DataSourceReader createReader(StructType schema, DataSourceOptions options);
}