[SPARK-2784][SQL] Deprecate hql() method in favor of a config option, 'spark.sql.dialect'

Many users have reported being confused by the distinction between the `sql` and `hql` methods.  Specifically, many users think that `sql(...)` cannot be used to read hive tables.  In this PR I introduce a new configuration option `spark.sql.dialect` that picks which dialect with be used for parsing.  For SQLContext this must be set to `sql`.  In `HiveContext` it defaults to `hiveql` but can also be set to `sql`.

The `hql` and `hiveql` methods continue to act the same but are now marked as deprecated.

**This is a possibly breaking change for some users unless they set the dialect manually, though this is unlikely.**

For example: `hiveContex.sql("SELECT 1")` will now throw a parsing exception by default.

Author: Michael Armbrust <michael@databricks.com>

Closes #1746 from marmbrus/sqlLanguageConf and squashes the following commits:

ad375cc [Michael Armbrust] Merge remote-tracking branch 'apache/master' into sqlLanguageConf
20c43f8 [Michael Armbrust] override function instead of just setting the value
7e4ae93 [Michael Armbrust] Deprecate hql() method in favor of a config option, 'spark.sql.dialect'

1 files changed, 6 insertions, 6 deletions

diff --git a/examples/src/main/scala/org/apache/spark/examples/sql/hive/HiveFromSpark.scala b/examples/src/main/scala/org/apache/spark/examples/sql/hive/HiveFromSpark.scala
index 12530c8490..3423fac0ad 100644
--- a/examples/src/main/scala/org/apache/spark/examples/sql/hive/HiveFromSpark.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/sql/hive/HiveFromSpark.scala
@@ -34,20 +34,20 @@ object HiveFromSpark {
     val hiveContext = new HiveContext(sc)
     import hiveContext._
 
-    hql("CREATE TABLE IF NOT EXISTS src (key INT, value STRING)")
-    hql("LOAD DATA LOCAL INPATH 'src/main/resources/kv1.txt' INTO TABLE src")
+    sql("CREATE TABLE IF NOT EXISTS src (key INT, value STRING)")
+    sql("LOAD DATA LOCAL INPATH 'src/main/resources/kv1.txt' INTO TABLE src")
 
     // Queries are expressed in HiveQL
     println("Result of 'SELECT *': ")
-    hql("SELECT * FROM src").collect.foreach(println)
+    sql("SELECT * FROM src").collect.foreach(println)
 
     // Aggregation queries are also supported.
-    val count = hql("SELECT COUNT(*) FROM src").collect().head.getLong(0)
+    val count = sql("SELECT COUNT(*) FROM src").collect().head.getLong(0)
     println(s"COUNT(*): $count")
 
     // The results of SQL queries are themselves RDDs and support all normal RDD functions.  The
     // items in the RDD are of type Row, which allows you to access each column by ordinal.
-    val rddFromSql = hql("SELECT key, value FROM src WHERE key < 10 ORDER BY key")
+    val rddFromSql = sql("SELECT key, value FROM src WHERE key < 10 ORDER BY key")
 
     println("Result of RDD.map:")
     val rddAsStrings = rddFromSql.map {
@@ -60,6 +60,6 @@ object HiveFromSpark {
 
     // Queries can then join RDD data with data stored in Hive.
     println("Result of SELECT *:")
-    hql("SELECT * FROM records r JOIN src s ON r.key = s.key").collect().foreach(println)
+    sql("SELECT * FROM records r JOIN src s ON r.key = s.key").collect().foreach(println)
   }
 }