spark SupportsPushDownRequiredColumns 源码
spark SupportsPushDownRequiredColumns 代码
文件路径：/sql/catalyst/src/main/java/org/apache/spark/sql/connector/read/SupportsPushDownRequiredColumns.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 org.apache.spark.annotation.Evolving;
import org.apache.spark.sql.types.StructType;
/**
* A mix-in interface for {@link ScanBuilder}. Data sources can implement this
* interface to push down required columns to the data source and only read these columns during
* scan to reduce the size of the data to be read.
*
* @since 3.0.0
*/
@Evolving
public interface SupportsPushDownRequiredColumns extends ScanBuilder {
/**
* Applies column pruning w.r.t. the given requiredSchema.
* <p>
* Implementation should try its best to prune the unnecessary columns or nested fields, but it's
* also OK to do the pruning partially, e.g., a data source may not be able to prune nested
* fields, and only prune top-level columns.
* <p>
* Note that, {@link Scan#readSchema()} implementation should take care of the column
* pruning applied here.
*/
void pruneColumns(StructType requiredSchema);
}
相关信息
相关文章
0
赞
热门推荐
-
2、 - 优质文章
-
3、 gate.io
-
7、 golang
-
9、 openharmony
-
10、 Vue中input框自动聚焦