sql_yacc.yy, set_var.h, set_var.cc:

  Optimization of SET NAMES

sql/set_var.cc

@@ -1655,6 +1655,34 @@ int set_var_password::update(THD *thd)
 	  1 : 0);
 }
 
+
+/*****************************************************************************
+  Functions to handle SET NAMES and SET CHARACTER SET
+*****************************************************************************/
+
+int set_var_client_collation::check(THD *thd)
+{
+  return 0;
+}
+
+int set_var_client_collation::update(THD *thd)
+{
+#if 0
+  if (var->type == OPT_GLOBAL)
+    global_system_variables.thd_charset= var->save_result.charset;
+  else
+#endif
+  {
+    thd->variables.thd_charset= client_collation;
+    thd->variables.convert_result_charset= convert_result_charset;
+    thd->protocol_simple.init(thd);
+    thd->protocol_prep.init(thd);
+  }
+  return 0;
+}
+
+
+
 /****************************************************************************
   Used templates
 ****************************************************************************/

sql/set_var.h

@@ -526,6 +526,21 @@ class set_var_password: public set_var_base
 };
 
 
+/* For SET NAMES and SET CHARACTER SET */
+
+class set_var_client_collation: public set_var_base
+{
+  CHARSET_INFO *client_collation;
+  my_bool convert_result_charset;
+public:
+  set_var_client_collation(CHARSET_INFO *coll_arg ,my_bool conv_arg)
+    :client_collation(coll_arg), convert_result_charset(conv_arg)
+  {}
+  int check(THD *thd);
+  int update(THD *thd);
+};
+
+
 /*
   Prototypes for helper functions
 */

sql/sql_yacc.yy

@@ -4409,19 +4409,13 @@ option_value:
 		         cl->name,cs->csname);
 	      YYABORT;
 	  }
-	  Item_string *csname= new Item_string(cl->name, 
-					       strlen(cl->name), 
-					       &my_charset_latin1);
-	  lex->var_list.push_back(new set_var(lex->option_type,
-					      find_sys_var("client_collation"),
-					      csname));
+	  lex->var_list.push_back(new set_var_client_collation(cl,1));
 	}
 	| COLLATION_SYM collation_name_or_default
 	{
 	  THD* thd= YYTHD;
 	  LEX *lex= &thd->lex;
-	  system_variables *vars= &thd->variables;
-	  CHARSET_INFO *cs= vars->thd_charset;
+	  CHARSET_INFO *cs= thd->variables->vars->thd_charset;
 	  CHARSET_INFO *cl= $2;
 
 	  if (!cl)
@@ -4438,12 +4432,7 @@ option_value:
 		         cl->name,cs->csname);
 	      YYABORT;
 	  }
-	  Item_string *csname= new Item_string(cl->name, 
-					       strlen(cl->name), 
-					       &my_charset_latin1);
-	  lex->var_list.push_back(new set_var(lex->option_type,
-					      find_sys_var("client_collation"),
-					      csname));
+	  lex->var_list.push_back(new set_var_client_collation(cl,1));
 	}
 	| PASSWORD equal text_or_password
 	  {