org.apache.spark.sql.sources.v2.ReadSupport 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,
* 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;
import org.apache.spark.annotation.InterfaceStability;
import org.apache.spark.sql.sources.DataSourceRegister;
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.
*/
@InterfaceStability.Evolving
public interface ReadSupport extends DataSourceV2 {
/**
* Creates a {@link DataSourceReader} to scan the data from this data source.
*
* If this method fails (by throwing an exception), the action will fail and no Spark job will be
* submitted.
*
* @param schema the user specified schema.
* @param options the options for the returned data source reader, which is an immutable
* case-insensitive string-to-string map.
*
* By default this method throws {@link UnsupportedOperationException}, implementations should
* override this method to handle user specified schema.
*/
default DataSourceReader createReader(StructType schema, DataSourceOptions options) {
String name;
if (this instanceof DataSourceRegister) {
name = ((DataSourceRegister) this).shortName();
} else {
name = this.getClass().getName();
}
throw new UnsupportedOperationException(name + " does not support user specified schema");
}
/**
* Creates a {@link DataSourceReader} to scan the data from this data source.
*
* If this method fails (by throwing an exception), the action will fail and no Spark job will be
* submitted.
*
* @param options the options for the returned data source reader, which is an immutable
* case-insensitive string-to-string map.
*/
DataSourceReader createReader(DataSourceOptions options);
}