[SQL] SPARK-1372 Support for caching and uncaching tables in a SQLContext.

This doesn't yet support different databases in Hive (though you can probably workaround this by calling `USE <dbname>`).  However, given the time constraints for 1.0 I think its probably worth including this now and extending the functionality in the next release.

Author: Michael Armbrust <michael@databricks.com>

Closes #282 from marmbrus/cacheTables and squashes the following commits:

83785db [Michael Armbrust] Support for caching and uncaching tables in a SQLContext.

3 files changed, 60 insertions, 0 deletions

diff --git a/sql/hive/src/test/resources/golden/read from cached table-0-ce3797dc14a603cba2a5e58c8612de5b b/sql/hive/src/test/resources/golden/read from cached table-0-ce3797dc14a603cba2a5e58c8612de5b
new file mode 100644
index 0000000000..60878ffb77
--- /dev/null
+++ b/sql/hive/src/test/resources/golden/read from cached table-0-ce3797dc14a603cba2a5e58c8612de5b
@@ -0,0 +1 @@
+238	val_238
diff --git a/sql/hive/src/test/resources/golden/read from uncached table-0-ce3797dc14a603cba2a5e58c8612de5b b/sql/hive/src/test/resources/golden/read from uncached table-0-ce3797dc14a603cba2a5e58c8612de5b
new file mode 100644
index 0000000000..60878ffb77
--- /dev/null
+++ b/sql/hive/src/test/resources/golden/read from uncached table-0-ce3797dc14a603cba2a5e58c8612de5b
@@ -0,0 +1 @@
+238	val_238
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/CachedTableSuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/CachedTableSuite.scala
new file mode 100644
index 0000000000..68d45e53cd
--- /dev/null
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/CachedTableSuite.scala
@@ -0,0 +1,58 @@
+/*
+ * 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.hive
+
+import org.apache.spark.sql.execution.SparkLogicalPlan
+import org.apache.spark.sql.columnar.InMemoryColumnarTableScan
+import org.apache.spark.sql.hive.execution.HiveComparisonTest
+
+class CachedTableSuite extends HiveComparisonTest {
+  TestHive.loadTestTable("src")
+
+  test("cache table") {
+    TestHive.cacheTable("src")
+  }
+
+  createQueryTest("read from cached table",
+    "SELECT * FROM src LIMIT 1")
+
+  test("check that table is cached and uncache") {
+    TestHive.table("src").queryExecution.analyzed match {
+      case SparkLogicalPlan(_ : InMemoryColumnarTableScan) => // Found evidence of caching
+      case noCache => fail(s"No cache node found in plan $noCache")
+    }
+    TestHive.uncacheTable("src")
+  }
+
+  createQueryTest("read from uncached table",
+    "SELECT * FROM src LIMIT 1")
+
+  test("make sure table is uncached") {
+    TestHive.table("src").queryExecution.analyzed match {
+      case cachePlan @ SparkLogicalPlan(_ : InMemoryColumnarTableScan) =>
+        fail(s"Table still cached after uncache: $cachePlan")
+      case noCache => // Table uncached successfully
+    }
+  }
+
+  test("correct error on uncache of non-cached table") {
+    intercept[IllegalArgumentException] {
+      TestHive.uncacheTable("src")
+    }
+  }
+}