Github user pnowojski commented on a diff in the pull request:
https://github.com/apache/flink/pull/6343#discussion_r202964290
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/catalog/ExternalTableUtil.scala
---
@@ -0,0 +1,148 @@
+/*
+ * 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.flink.table.catalog
+
+import java.util
+
+import org.apache.flink.table.api._
+import org.apache.flink.table.descriptors.DescriptorProperties
+import org.apache.flink.table.factories._
+import org.apache.flink.table.plan.schema._
+import org.apache.flink.table.plan.stats.FlinkStatistic
+import org.apache.flink.table.util.Logging
+
+
+/**
+ * The utility class is used to convert [[ExternalCatalogTable]] to
[[TableSourceSinkTable]].
+ *
+ * It uses [[TableFactoryService]] for discovering.
+ */
+object ExternalTableUtil extends Logging {
+
+ /**
+ * Converts an [[ExternalCatalogTable]] instance to a
[[TableSourceTable]] instance
+ *
+ * @param externalCatalogTable the [[ExternalCatalogTable]] instance
which to convert
+ * @return converted [[TableSourceTable]] instance from the input
catalog table
+ */
+ def fromExternalCatalogTable[T1, T2](
+ tableEnv: TableEnvironment,
+ externalCatalogTable: ExternalCatalogTable)
+ : TableSourceSinkTable[T1, T2] = {
+
+ val properties = new DescriptorProperties()
+ externalCatalogTable.addProperties(properties)
+ val javaMap = properties.asMap
+ val statistics = new FlinkStatistic(externalCatalogTable.getTableStats)
+
+ val source: Option[TableSourceTable[T1]] = tableEnv match {
+ // check for a batch table source in this batch environment
+ case _: BatchTableEnvironment if externalCatalogTable.isBatchTable =>
+ createBatchTableSource(externalCatalogTable, javaMap, statistics)
+
+ // check for a stream table source in this stream environment
+ case _: StreamTableEnvironment if externalCatalogTable.isStreamTable
=>
+ createStreamTableSource(externalCatalogTable, javaMap, statistics)
+
+ case _ =>
+ throw new ValidationException(
+ "External catalog table does not support the current environment
for a table source.")
+ }
+
+ val sink: Option[TableSinkTable[T2]] = tableEnv match {
+ // check for a batch table sink in this batch environment
+ case _: BatchTableEnvironment if externalCatalogTable.isBatchTable =>
+ createBatchTableSink(externalCatalogTable, javaMap, statistics)
+
+ // check for a stream table sink in this stream environment
+ case _: StreamTableEnvironment if externalCatalogTable.isStreamTable
=>
+ createStreamTableSink(externalCatalogTable, javaMap, statistics)
+
+ case _ =>
+ throw new ValidationException(
+ "External catalog table does not support the current environment
for a table sink.")
+ }
+
+ new TableSourceSinkTable[T1, T2](source, sink)
+ }
+
+ private def createBatchTableSource[T](
--- End diff --
I still do not like this lack of abstraction between batch and streaming in
form of `createBatchTableSource`/`createStreamTableSource`.
Instead of writing if/elses everywhere in our code there should be some
common layer that handles such logic. Here half of the problem boils down to
factories with methods createBatchTableSource and createStreamTableSource.
---
