Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/16233#discussion_r95678535
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/view.scala
---
@@ -0,0 +1,80 @@
+/*
+ * 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.analysis
+
+import org.apache.spark.sql.AnalysisException
+import org.apache.spark.sql.catalyst.CatalystConf
+import org.apache.spark.sql.catalyst.expressions.{Alias, Attribute, Cast}
+import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, Project,
View}
+import org.apache.spark.sql.catalyst.rules.Rule
+
+/**
+ * This file defines analysis rules related to views.
+ */
+
+/**
+ * Make sure that a view's child plan produces the view's output
attributes. We wrap the child
+ * with a Project and add an alias for each output attribute. The
attributes are resolved by
+ * name. This should be only done after the batch of Resolution, because
the view attributes are
+ * not completely resolved during the batch of Resolution.
+ */
+case class AliasViewChild(conf: CatalystConf) extends Rule[LogicalPlan] {
+ override def apply(plan: LogicalPlan): LogicalPlan = plan
resolveOperators {
+ case v @ View(_, output, child) if child.resolved =>
+ val resolver = conf.resolver
+ val newOutput = output.map { attr =>
+ val originAttr = findAttributeByName(attr.name, child.output,
resolver)
+ // The dataType of the output attributes may be not the same with
that of the view output,
+ // so we should cast the attribute to the dataType of the view
output attribute. If the
+ // cast can't perform, will throw an AnalysisException.
+ Alias(Cast(originAttr, attr.dataType), attr.name)(exprId =
attr.exprId,
+ qualifier = attr.qualifier, explicitMetadata =
Some(attr.metadata))
--- End diff --
Agree.
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