Address comments

Author: dssysolyatin

babel/src/main/java/org/apache/calcite/sql/babel/postgres/SqlSetOptions.java

@@ -67,10 +67,6 @@ public enum Names implements Symbolizable {
    */
   public enum Values implements Symbolizable {
     NONE,
-    LOCAL;
-
-    @Override public String toString() {
-      return super.toString().replace("_", " ");
-    }
+    LOCAL
   }
 }

babel/src/test/java/org/apache/calcite/test/BabelParserTest.java

@@ -392,8 +392,6 @@ private void checkParseInfixCast(String sqlType) {
     f.sql("SET timezone = 'PST8PDT'")
             .ok("SET \"timezone\" = 'PST8PDT'");
 
-    f.sql("SET SESSION AUTHORIZATION DEFAULT")
-        .ok("SET \"session_authorization\" = DEFAULT");
     f.sql("SET SESSION AUTHORIZATION DEFAULT")
         .ok("SET \"session_authorization\" = DEFAULT");
 
@@ -420,13 +418,17 @@ private void checkParseInfixCast(String sqlType) {
   @Test void testPostgresSqlReset() {
     SqlParserFixture f = fixture().withDialect(PostgresqlSqlDialect.DEFAULT);
 
+    /*
+    * RESET ROLE, RESET SESSION AUTHORIZATION, RESET TRANSACTION ISOLATION LEVEL, and RESET TIME ZONE
+    * are simply syntactic sugar for a more unified syntax RESET "<variable_name>".
+    */
     f.sql("RESET ALL").same();
     f.sql("RESET ROLE")
         .ok("RESET \"role\"");
     f.sql("RESET SESSION AUTHORIZATION")
         .ok("RESET \"session_authorization\"");
-    f.sql("RESET SESSION AUTHORIZATION")
-        .ok("RESET \"session_authorization\"");
+    f.sql("RESET TRANSACTION ISOLATION LEVEL")
+        .ok("RESET \"transaction_isolation\"");
     f.sql("RESET TIME ZONE")
         .ok("RESET \"timezone\"");
     f.sql("RESET autovacuum")

site/_docs/babel_reference.md

@@ -77,8 +77,8 @@ limitations under the License.
 }
 </style>
 
-The page describes SQL expressions that are recognized by Calcite's babel SQL parser
-in addition to the expressions recognized by [Calcite's default SQL parser](reference.html).
+The page describes SQL statements and expressions that are recognized by Calcite's Babel SQL parser,
+in addition to those recognized by [Calcite's default SQL parser](reference.html).
 
 ## Grammar