[SPARK-7961][SQL]Refactor SQLConf to display better error message

1. Add `SQLConfEntry` to store the information about a configuration. For those configurations that cannot be found in `sql-programming-guide.md`, I left the doc as `<TODO>`.
2. Verify the value when setting a configuration if this is in SQLConf.
3. Use `SET -v` to display all public configurations.

Author: zsxwing <zsxwing@gmail.com>

Closes #6747 from zsxwing/sqlconf and squashes the following commits:

7d09bad [zsxwing] Use SQLConfEntry in HiveContext
49f6213 [zsxwing] Add getConf, setConf to SQLContext and HiveContext
e014f53 [zsxwing] Merge branch 'master' into sqlconf
93dad8e [zsxwing] Fix the unit tests
cf950c1 [zsxwing] Fix the code style and tests
3c5f03e [zsxwing] Add unsetConf(SQLConfEntry) and fix the code style
a2f4add [zsxwing] getConf will return the default value if a config is not set
037b1db [zsxwing] Add schema to SetCommand
0520c3c [zsxwing] Merge branch 'master' into sqlconf
7afb0ec [zsxwing] Fix the configurations about HiveThriftServer
7e728e3 [zsxwing] Add doc for SQLConfEntry and fix 'toString'
5e95b10 [zsxwing] Add enumConf
c6ba76d [zsxwing] setRawString => setConfString, getRawString => getConfString
4abd807 [zsxwing] Fix the test for 'set -v'
6e47e56 [zsxwing] Fix the compilation error
8973ced [zsxwing] Remove floatConf
1fc3a8b [zsxwing] Remove the 'conf' command and use 'set -v' instead
99c9c16 [zsxwing] Fix tests that use SQLConfEntry as a string
88a03cc [zsxwing] Add new lines between confs and return types
ce7c6c8 [zsxwing] Remove seqConf
f3c1b33 [zsxwing] Refactor SQLConf to display better error message

2 files changed, 6 insertions, 6 deletions

diff --git a/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/HiveCompatibilitySuite.scala b/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/HiveCompatibilitySuite.scala
index 82c0b49459..432de2564d 100644
--- a/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/HiveCompatibilitySuite.scala
+++ b/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/HiveCompatibilitySuite.scala
@@ -47,17 +47,17 @@ class HiveCompatibilitySuite extends HiveQueryFileTest with BeforeAndAfter {
     // Add Locale setting
     Locale.setDefault(Locale.US)
     // Set a relatively small column batch size for testing purposes
-    TestHive.setConf(SQLConf.COLUMN_BATCH_SIZE, "5")
+    TestHive.setConf(SQLConf.COLUMN_BATCH_SIZE, 5)
     // Enable in-memory partition pruning for testing purposes
-    TestHive.setConf(SQLConf.IN_MEMORY_PARTITION_PRUNING, "true")
+    TestHive.setConf(SQLConf.IN_MEMORY_PARTITION_PRUNING, true)
   }
 
   override def afterAll() {
     TestHive.cacheTables = false
     TimeZone.setDefault(originalTimeZone)
     Locale.setDefault(originalLocale)
-    TestHive.setConf(SQLConf.COLUMN_BATCH_SIZE, originalColumnBatchSize.toString)
-    TestHive.setConf(SQLConf.IN_MEMORY_PARTITION_PRUNING, originalInMemoryPartitionPruning.toString)
+    TestHive.setConf(SQLConf.COLUMN_BATCH_SIZE, originalColumnBatchSize)
+    TestHive.setConf(SQLConf.IN_MEMORY_PARTITION_PRUNING, originalInMemoryPartitionPruning)
   }
 
   /** A list of tests deemed out of scope currently and thus completely disregarded. */
diff --git a/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/SortMergeCompatibilitySuite.scala b/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/SortMergeCompatibilitySuite.scala
index 65d070bd3c..f458567e5d 100644
--- a/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/SortMergeCompatibilitySuite.scala
+++ b/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/SortMergeCompatibilitySuite.scala
@@ -26,11 +26,11 @@ import org.apache.spark.sql.hive.test.TestHive
 class SortMergeCompatibilitySuite extends HiveCompatibilitySuite {
   override def beforeAll() {
     super.beforeAll()
-    TestHive.setConf(SQLConf.SORTMERGE_JOIN, "true")
+    TestHive.setConf(SQLConf.SORTMERGE_JOIN, true)
   }
 
   override def afterAll() {
-    TestHive.setConf(SQLConf.SORTMERGE_JOIN, "false")
+    TestHive.setConf(SQLConf.SORTMERGE_JOIN, false)
     super.afterAll()
   }