Github user rdblue commented on a diff in the pull request:
https://github.com/apache/spark/pull/22547#discussion_r226785695
--- Diff:
sql/core/src/main/java/org/apache/spark/sql/sources/v2/reader/BatchScan.java ---
@@ -0,0 +1,43 @@
+/*
+ * 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.reader;
+
+import org.apache.spark.annotation.InterfaceStability;
+import org.apache.spark.sql.sources.v2.DataSourceOptions;
+import org.apache.spark.sql.sources.v2.SupportsBatchRead;
+import org.apache.spark.sql.sources.v2.Table;
+
+/**
+ * A {@link Scan} for batch queries.
+ *
+ * The execution engine will get an instance of {@link Table} first, then
call
+ * {@link Table#newScanConfigBuilder(DataSourceOptions)} and create an
instance of
+ * {@link ScanConfig}. The {@link ScanConfigBuilder} can apply operator
pushdown and keep the
+ * pushdown result in {@link ScanConfig}. Then
+ * {@link SupportsBatchRead#createBatchScan(ScanConfig,
DataSourceOptions)} will be called to create
+ * a {@link BatchScan} instance, which will be used to create input
partitions and reader factory to
+ * scan data from the data source with a Spark job.
+ */
[email protected]
+public interface BatchScan extends Scan {
+
+ /**
+ * Returns a factory, which produces one {@link PartitionReader} for one
{@link InputPartition}.
+ */
+ PartitionReaderFactory createReaderFactory();
--- End diff --
Why are `BatchScan` and `PartitionReaderFactory` different interfaces?
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