[SPARK-20487][SQL] HiveTableScan node is quite verbose in explained…

… plan

## What changes were proposed in this pull request?

Changed `TreeNode.argString` to handle `CatalogTable` separately (otherwise it would call the default `toString` on the `CatalogTable`)

## How was this patch tested?

- Expanded scope of existing unit test to ensure that verbose information is not present
- Manual testing

Before

```
scala> hc.sql(" SELECT * FROM my_table WHERE name = 'foo' ").explain(true)
== Parsed Logical Plan ==
'Project [*]
+- 'Filter ('name = foo)
   +- 'UnresolvedRelation `my_table`

== Analyzed Logical Plan ==
user_id: bigint, name: string, ds: string
Project [user_id#13L, name#14, ds#15]
+- Filter (name#14 = foo)
   +- SubqueryAlias my_table
      +- CatalogRelation CatalogTable(
Database: default
Table: my_table
Owner: tejasp
Created: Fri Apr 14 17:05:50 PDT 2017
Last Access: Wed Dec 31 16:00:00 PST 1969
Type: MANAGED
Provider: hive
Properties: [serialization.format=1]
Statistics: 9223372036854775807 bytes
Location: file:/tmp/warehouse/my_table
Serde Library: org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe
InputFormat: org.apache.hadoop.mapred.TextInputFormat
OutputFormat: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat
Partition Provider: Catalog
Partition Columns: [`ds`]
Schema: root
-- user_id: long (nullable = true)
-- name: string (nullable = true)
-- ds: string (nullable = true)
), [user_id#13L, name#14], [ds#15]

== Optimized Logical Plan ==
Filter (isnotnull(name#14) && (name#14 = foo))
+- CatalogRelation CatalogTable(
Database: default
Table: my_table
Owner: tejasp
Created: Fri Apr 14 17:05:50 PDT 2017
Last Access: Wed Dec 31 16:00:00 PST 1969
Type: MANAGED
Provider: hive
Properties: [serialization.format=1]
Statistics: 9223372036854775807 bytes
Location: file:/tmp/warehouse/my_table
Serde Library: org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe
InputFormat: org.apache.hadoop.mapred.TextInputFormat
OutputFormat: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat
Partition Provider: Catalog
Partition Columns: [`ds`]
Schema: root
-- user_id: long (nullable = true)
-- name: string (nullable = true)
-- ds: string (nullable = true)
), [user_id#13L, name#14], [ds#15]

== Physical Plan ==
*Filter (isnotnull(name#14) && (name#14 = foo))
+- HiveTableScan [user_id#13L, name#14, ds#15], CatalogRelation CatalogTable(
Database: default
Table: my_table
Owner: tejasp
Created: Fri Apr 14 17:05:50 PDT 2017
Last Access: Wed Dec 31 16:00:00 PST 1969
Type: MANAGED
Provider: hive
Properties: [serialization.format=1]
Statistics: 9223372036854775807 bytes
Location: file:/tmp/warehouse/my_table
Serde Library: org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe
InputFormat: org.apache.hadoop.mapred.TextInputFormat
OutputFormat: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat
Partition Provider: Catalog
Partition Columns: [`ds`]
Schema: root
-- user_id: long (nullable = true)
-- name: string (nullable = true)
-- ds: string (nullable = true)
), [user_id#13L, name#14], [ds#15]
```

After

```
scala> hc.sql(" SELECT * FROM my_table WHERE name = 'foo' ").explain(true)
== Parsed Logical Plan ==
'Project [*]
+- 'Filter ('name = foo)
   +- 'UnresolvedRelation `my_table`

== Analyzed Logical Plan ==
user_id: bigint, name: string, ds: string
Project [user_id#13L, name#14, ds#15]
+- Filter (name#14 = foo)
   +- SubqueryAlias my_table
      +- CatalogRelation `default`.`my_table`, [user_id#13L, name#14], [ds#15]

== Optimized Logical Plan ==
Filter (isnotnull(name#14) && (name#14 = foo))
+- CatalogRelation `default`.`my_table`, [user_id#13L, name#14], [ds#15]

== Physical Plan ==
*Filter (isnotnull(name#14) && (name#14 = foo))
+- HiveTableScan [user_id#13L, name#14, ds#15], CatalogRelation `default`.`my_table`, [user_id#13L, name#14], [ds#15]
```

Author: Tejas Patil <[email protected]>

Closes #17780 from tejasapatil/SPARK-20487_verbose_plan.

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/trees/TreeNode.scala

@@ -444,6 +444,7 @@ abstract class TreeNode[BaseType <: TreeNode[BaseType]] extends Product {
     case None => Nil
     case Some(null) => Nil
     case Some(any) => any :: Nil
+    case table: CatalogTable => table.identifier :: Nil
     case other => other :: Nil
   }.mkString(", ")
 

sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveExplainSuite.scala

@@ -47,7 +47,23 @@ class HiveExplainSuite extends QueryTest with SQLTestUtils with TestHiveSingleto
     checkKeywordsNotExist(sql(" explain   select * from src where key=123 "),
                    "== Parsed Logical Plan ==",
                    "== Analyzed Logical Plan ==",
-                   "== Optimized Logical Plan ==")
+                   "== Optimized Logical Plan ==",
+                   "Owner",
+                   "Database",
+                   "Created",
+                   "Last Access",
+                   "Type",
+                   "Provider",
+                   "Properties",
+                   "Statistics",
+                   "Location",
+                   "Serde Library",
+                   "InputFormat",
+                   "OutputFormat",
+                   "Partition Provider",
+                   "Schema"
+    )
+
     checkKeywordsExist(sql(" explain   extended select * from src where key=123 "),
                    "== Parsed Logical Plan ==",
                    "== Analyzed Logical Plan ==",