[SPARK-17068][SQL] Make view-usage visible during analysis

## What changes were proposed in this pull request?
This PR adds a field to subquery alias in order to make the usage of views in a resolved `LogicalPlan` more visible (and more understandable).

For example, the following view and query:
```sql
create view constants as select 1 as id union all select 1 union all select 42
select * from constants;
```
...now yields the following analyzed plan:
```
Project [id#39]
+- SubqueryAlias c, `default`.`constants`
   +- Project [gen_attr_0#36 AS id#39]
      +- SubqueryAlias gen_subquery_0
         +- Union
            :- Union
            :  :- Project [1 AS gen_attr_0#36]
            :  :  +- OneRowRelation$
            :  +- Project [1 AS gen_attr_1#37]
            :     +- OneRowRelation$
            +- Project [42 AS gen_attr_2#38]
               +- OneRowRelation$
```
## How was this patch tested?
Added tests for the two code paths in `SessionCatalogSuite` (sql/core) and `HiveMetastoreCatalogSuite` (sql/hive)

Author: Herman van Hovell <hvanhovell@databricks.com>

Closes #14657 from hvanhovell/SPARK-17068.

3 files changed, 5 insertions, 5 deletions

diff --git a/sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala b/sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala
index c119df83b3..6da99ce0dd 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/Dataset.scala
@@ -967,7 +967,7 @@ class Dataset[T] private[sql](
    * @since 1.6.0
    */
   def as(alias: String): Dataset[T] = withTypedPlan {
-    SubqueryAlias(alias, logicalPlan)
+    SubqueryAlias(alias, logicalPlan, None)
   }
 
   /**
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/catalyst/SQLBuilder.scala b/sql/core/src/main/scala/org/apache/spark/sql/catalyst/SQLBuilder.scala
index 5d93419f35..ff8e0f2642 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/catalyst/SQLBuilder.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/catalyst/SQLBuilder.scala
@@ -75,7 +75,7 @@ class SQLBuilder private (
     val aliasedOutput = canonicalizedPlan.output.zip(outputNames).map {
       case (attr, name) => Alias(attr.withQualifier(None), name)()
     }
-    val finalPlan = Project(aliasedOutput, SubqueryAlias(finalName, canonicalizedPlan))
+    val finalPlan = Project(aliasedOutput, SubqueryAlias(finalName, canonicalizedPlan, None))
 
     try {
       val replaced = finalPlan.transformAllExpressions {
@@ -440,7 +440,7 @@ class SQLBuilder private (
 
     object RemoveSubqueriesAboveSQLTable extends Rule[LogicalPlan] {
       override def apply(plan: LogicalPlan): LogicalPlan = plan transformUp {
-        case SubqueryAlias(_, t @ ExtractSQLTable(_)) => t
+        case SubqueryAlias(_, t @ ExtractSQLTable(_), _) => t
       }
     }
 
@@ -557,7 +557,7 @@ class SQLBuilder private (
     }
 
     private def addSubquery(plan: LogicalPlan): SubqueryAlias = {
-      SubqueryAlias(newSubqueryName(), plan)
+      SubqueryAlias(newSubqueryName(), plan, None)
     }
 
     private def addSubqueryIfNeeded(plan: LogicalPlan): LogicalPlan = plan match {
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/rules.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/rules.scala
index fc8d8c3667..5eb2f0a9ff 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/rules.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/rules.scala
@@ -55,7 +55,7 @@ class ResolveDataSource(sparkSession: SparkSession) extends Rule[LogicalPlan] {
             s"${u.tableIdentifier.database.get}")
         }
         val plan = LogicalRelation(dataSource.resolveRelation())
-        u.alias.map(a => SubqueryAlias(u.alias.get, plan)).getOrElse(plan)
+        u.alias.map(a => SubqueryAlias(u.alias.get, plan, None)).getOrElse(plan)
       } catch {
         case e: ClassNotFoundException => u
         case e: Exception =>