Github user chenghao-intel commented on a diff in the pull request:
https://github.com/apache/spark/pull/3249#discussion_r25551625
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/SubqueryExpression.scala
---
@@ -0,0 +1,39 @@
+/*
+ * 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.catalyst.expressions
+
+import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan
+
+/**
+ * Evaluates whether `subquery` result contains `value`.
+ * For example : 'SELECT * FROM src a WHERE a.key in (SELECT b.key FROM
src b)'
+ * @param subquery In the above example 'SELECT b.key FROM src b' is
'subquery'
+ */
+case class SubqueryExpression(subquery: LogicalPlan) extends Expression {
--- End diff --
Instead of making the Subquery as a fake expression, a better idea probably
create a new logical plan like
```
SubQueryIn(left: LogicalPlan, nested: LogicalPlan, isNotIn:Boolean)
```
That's also how I implement the `EXISTS` at
https://github.com/apache/spark/pull/4812/files#diff-9a11e98e8f4bd1c4bb18ca6a7a7b8948R262
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastruct...@apache.org or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org
For additional commands, e-mail: reviews-h...@spark.apache.org
