[SPARK-12855][MINOR][SQL][DOC][TEST] remove spark.sql.dialect from do…

…c and test

## What changes were proposed in this pull request?

Since developer API of plug-able parser has been removed in #10801 , docs should be updated accordingly.

## How was this patch tested?

This patch will not affect the real code path.

Author: Daoyuan Wang <daoyuan.wang@intel.com>

Closes #11758 from adrian-wang/spark12855.

docs/sql-programming-guide.md

@@ -122,13 +122,6 @@ Spark build. If these dependencies are not a problem for your application then u
 is recommended for the 1.3 release of Spark. Future releases will focus on bringing `SQLContext` up
 to feature parity with a `HiveContext`.
 
-The specific variant of SQL that is used to parse queries can also be selected using the
-`spark.sql.dialect` option. This parameter can be changed using either the `setConf` method on
-a `SQLContext` or by using a `SET key=value` command in SQL. For a `SQLContext`, the only dialect
-available is "sql" which uses a simple SQL parser provided by Spark SQL. In a `HiveContext`, the
-default is "hiveql", though "sql" is also available. Since the HiveQL parser is much more complete,
-this is recommended for most use cases.
-
 
 ## Creating DataFrames
 

sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala

@@ -80,7 +80,7 @@ class SQLContext private[sql](
   def this(sparkContext: JavaSparkContext) = this(sparkContext.sc)
 
   // If spark.sql.allowMultipleContexts is true, we will throw an exception if a user
-  // wants to create a new root SQLContext (a SLQContext that is not created by newSession).
+  // wants to create a new root SQLContext (a SQLContext that is not created by newSession).
   private val allowMultipleContexts =
     sparkContext.conf.getBoolean(
       SQLConf.ALLOW_MULTIPLE_CONTEXTS.key,

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

@@ -270,12 +270,6 @@ class HiveQuerySuite extends HiveComparisonTest with BeforeAndAfter {
     "SELECT 11 % 10, IF((101.1 % 100.0) BETWEEN 1.01 AND 1.11, \"true\", \"false\"), " +
       "(101 / 2) % 10 FROM src LIMIT 1")
 
-  test("Query expressed in SQL") {
-    setConf("spark.sql.dialect", "sql")
-    assert(sql("SELECT 1").collect() === Array(Row(1)))
-    setConf("spark.sql.dialect", "hiveql")
-  }
-
   test("Query expressed in HiveQL") {
     sql("FROM src SELECT key").collect()
   }