[SPARK-5286][SQL] Fail to drop an invalid table when using the data source API

JIRA: https://issues.apache.org/jira/browse/SPARK-5286

Author: Yin Huai <yhuai@databricks.com>

Closes #4076 from yhuai/SPARK-5286 and squashes the following commits:

6b69ed1 [Yin Huai] Catch all exception when we try to uncache a query.

sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/commands.scala

@@ -56,7 +56,12 @@ case class DropTable(
     try {
       hiveContext.tryUncacheQuery(hiveContext.table(tableName))
     } catch {
+      // This table's metadata is not in
       case _: org.apache.hadoop.hive.ql.metadata.InvalidTableException =>
+      // Other exceptions can be caused by users providing wrong parameters in OPTIONS
+      // (e.g. invalid paths). We catch it and log a warning message.
+      // Users should be able to drop such kinds of tables regardless if there is an exception.
+      case e: Exception => log.warn(s"${e.getMessage}")
     }
     hiveContext.invalidateTable(tableName)
     hiveContext.runSqlHive(s"DROP TABLE $ifExistsClause$tableName")

sql/hive/src/test/scala/org/apache/spark/sql/hive/MetastoreDataSourcesSuite.scala

@@ -242,4 +242,17 @@ class MetastoreDataSourcesSuite extends QueryTest with BeforeAndAfterEach {
 
     assert(expectedSchema == table("jsonTable").schema)
   }
+
+  test("SPARK-5286 Fail to drop an invalid table when using the data source API") {
+    sql(
+      s"""
+        |CREATE TABLE jsonTable
+        |USING org.apache.spark.sql.json.DefaultSource
+        |OPTIONS (
+        |  path 'it is not a path at all!'
+        |)
+      """.stripMargin)
+
+    sql("DROP TABLE jsonTable").collect.foreach(println)
+  }
 }