org.apache.spark.sql.sources.v2.reader.SupportsReportStatistics 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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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.spark.sql.sources.v2.reader;
import org.apache.spark.annotation.InterfaceStability;
/**
* A mix in interface for {@link DataSourceReader}. Data source readers can implement this
* interface to report statistics to Spark.
*
* As of Spark 2.4, statistics are reported to the optimizer before any operator is pushed to the
* DataSourceReader. Implementations that return more accurate statistics based on pushed operators
* will not improve query performance until the planner can push operators before getting stats.
*/
@InterfaceStability.Evolving
public interface SupportsReportStatistics extends DataSourceReader {
/**
* Returns the estimated statistics of this data source.
*/
Statistics estimateStatistics();
}