diff --git a/mysql-test/r/lock_multi.result b/mysql-test/r/lock_multi.result
index 6d31d01d154..b04a5fb0a3e 100644
--- a/mysql-test/r/lock_multi.result
+++ b/mysql-test/r/lock_multi.result
@@ -50,14 +50,6 @@ Field	Type	Null	Key	Default	Extra
 a	int(11)	YES		NULL	
 unlock tables;
 drop table t1;
-CREATE DATABASE mysqltest_1;
-FLUSH TABLES WITH READ LOCK;
- DROP DATABASE mysqltest_1;
-DROP DATABASE mysqltest_1;
-ERROR HY000: Can't execute the query because you have a conflicting read lock
-UNLOCK TABLES;
-DROP DATABASE mysqltest_1;
-ERROR HY000: Can't drop database 'mysqltest_1'; database doesn't exist
 use mysql;
 LOCK TABLES columns_priv WRITE, db WRITE, host WRITE, user WRITE;
 FLUSH TABLES;
@@ -74,3 +66,11 @@ Select_priv
 N
 use test;
 use test;
+CREATE DATABASE mysqltest_1;
+FLUSH TABLES WITH READ LOCK;
+ DROP DATABASE mysqltest_1;
+DROP DATABASE mysqltest_1;
+ERROR HY000: Can't execute the query because you have a conflicting read lock
+UNLOCK TABLES;
+DROP DATABASE mysqltest_1;
+ERROR HY000: Can't drop database 'mysqltest_1'; database doesn't exist
diff --git a/mysql-test/t/lock_multi.test b/mysql-test/t/lock_multi.test
index 7fc65f52214..d0577d6f2f3 100644
--- a/mysql-test/t/lock_multi.test
+++ b/mysql-test/t/lock_multi.test
@@ -128,6 +128,36 @@ unlock tables;
 drop table t1;
 
 #
+# Bug#16986 - Deadlock condition with MyISAM tables
+#
+connection locker;
+use mysql;
+LOCK TABLES columns_priv WRITE, db WRITE, host WRITE, user WRITE;
+FLUSH TABLES;
+--sleep 1
+#
+connection reader;
+use mysql;
+#NOTE:  This must be a multi-table select, otherwise the deadlock will not occur
+send SELECT user.Select_priv FROM user, db WHERE user.user = db.user LIMIT 1;
+--sleep 1
+#
+connection locker;
+# Make test case independent from earlier grants.
+--replace_result "Table is already up to date" "OK"
+OPTIMIZE TABLES columns_priv, db, host, user;
+UNLOCK TABLES;
+#
+connection reader;
+reap;
+use test;
+#
+connection locker;
+use test;
+#
+connection default;
+
+# End of 5.0 tests
 # Bug#19815 - CREATE/RENAME/DROP DATABASE can deadlock on a global read lock
 #
 connect (con1,localhost,root,,);
@@ -161,33 +191,3 @@ disconnect con2;
 --error ER_DB_DROP_EXISTS
 DROP DATABASE mysqltest_1;
 
-# Bug#16986 - Deadlock condition with MyISAM tables
-#
-connection locker;
-use mysql;
-LOCK TABLES columns_priv WRITE, db WRITE, host WRITE, user WRITE;
-FLUSH TABLES;
---sleep 1
-#
-connection reader;
-use mysql;
-#NOTE:  This must be a multi-table select, otherwise the deadlock will not occur
-send SELECT user.Select_priv FROM user, db WHERE user.user = db.user LIMIT 1;
---sleep 1
-#
-connection locker;
-# Make test case independent from earlier grants.
---replace_result "Table is already up to date" "OK"
-OPTIMIZE TABLES columns_priv, db, host, user;
-UNLOCK TABLES;
-#
-connection reader;
-reap;
-use test;
-#
-connection locker;
-use test;
-#
-connection default;
-
-# End of 5.0 tests
diff --git a/sql/handler.cc b/sql/handler.cc
index 81c42f9da15..47bcf1caba1 100644
--- a/sql/handler.cc
+++ b/sql/handler.cc
@@ -68,14 +68,14 @@ ulong total_ha_2pc= 0;
 /* size of savepoint storage area (see ha_init) */
 ulong savepoint_alloc_size= 0;
 
-struct show_table_alias_st sys_table_aliases[]=
+static const LEX_STRING sys_table_aliases[]=
 {
-  {"INNOBASE",  DB_TYPE_INNODB},
-  {"NDB",       DB_TYPE_NDBCLUSTER},
-  {"BDB",       DB_TYPE_BERKELEY_DB},
-  {"HEAP",      DB_TYPE_HEAP},
-  {"MERGE",     DB_TYPE_MRG_MYISAM},
-  {NullS,       DB_TYPE_UNKNOWN}
+  {(char*)STRING_WITH_LEN("INNOBASE")},  {(char*)STRING_WITH_LEN("INNODB")},
+  {(char*)STRING_WITH_LEN("NDB")},       {(char*)STRING_WITH_LEN("NDBCLUSTER")},
+  {(char*)STRING_WITH_LEN("BDB")},       {(char*)STRING_WITH_LEN("BERKELEYDB")},
+  {(char*)STRING_WITH_LEN("HEAP")},      {(char*)STRING_WITH_LEN("MEMORY")},
+  {(char*)STRING_WITH_LEN("MERGE")},     {(char*)STRING_WITH_LEN("MRG_MYISAM")},
+  {NullS, 0}
 };
 
 const char *ha_row_type[] = {
@@ -91,15 +91,50 @@ TYPELIB tx_isolation_typelib= {array_elements(tx_isolation_names)-1,"",
 static TYPELIB known_extensions= {0,"known_exts", NULL, NULL};
 uint known_extensions_id= 0;
 
-handlerton *ha_resolve_by_name(THD *thd, LEX_STRING *name)
+
+/*
+  Return the default storage engine handlerton for thread
+  
+  SYNOPSIS
+    ha_default_handlerton(thd)
+    thd         current thread
+  
+  RETURN
+    pointer to handlerton
+*/
+
+handlerton *ha_default_handlerton(THD *thd)
 {
-  show_table_alias_st *table_alias;
+  return (thd->variables.table_type != NULL) ?
+          thd->variables.table_type :
+          (global_system_variables.table_type != NULL ?
+           global_system_variables.table_type : &myisam_hton);
+}
+
+
+/*
+  Return the storage engine handlerton for the supplied name
+  
+  SYNOPSIS
+    ha_resolve_by_name(thd, name)
+    thd         current thread
+    name        name of storage engine
+  
+  RETURN
+    pointer to handlerton
+*/
+
+handlerton *ha_resolve_by_name(THD *thd, const LEX_STRING *name)
+{
+  const LEX_STRING *table_alias;
   st_plugin_int *plugin;
 
-  if (thd && !my_strnncoll(&my_charset_latin1,
+redo:
+  /* my_strnncoll is a macro and gcc doesn't do early expansion of macro */
+  if (thd && !my_charset_latin1.coll->strnncoll(&my_charset_latin1,
                            (const uchar *)name->str, name->length,
-                           (const uchar *)"DEFAULT", 7))
-    return ha_resolve_by_legacy_type(thd, DB_TYPE_DEFAULT);
+                           (const uchar *)STRING_WITH_LEN("DEFAULT"), 0))
+    return ha_default_handlerton(thd);
 
   if ((plugin= plugin_lock(name, MYSQL_STORAGE_ENGINE_PLUGIN)))
   {
@@ -112,13 +147,15 @@ handlerton *ha_resolve_by_name(THD *thd, LEX_STRING *name)
   /*
     We check for the historical aliases.
   */
-  for (table_alias= sys_table_aliases; table_alias->type; table_alias++)
+  for (table_alias= sys_table_aliases; table_alias->str; table_alias+= 2)
   {
     if (!my_strnncoll(&my_charset_latin1,
                       (const uchar *)name->str, name->length,
-                      (const uchar *)table_alias->alias,
-                      strlen(table_alias->alias)))
-      return ha_resolve_by_legacy_type(thd, table_alias->type);
+                      (const uchar *)table_alias->str, table_alias->length))
+    {
+      name= table_alias + 1;
+      goto redo;
+    }
   }
 
   return NULL;
@@ -130,20 +167,20 @@ const char *ha_get_storage_engine(enum legacy_db_type db_type)
   switch (db_type) {
   case DB_TYPE_DEFAULT:
     return "DEFAULT";
-  case DB_TYPE_UNKNOWN:
-    return "UNKNOWN";
   default:
     if (db_type > DB_TYPE_UNKNOWN && db_type < DB_TYPE_DEFAULT &&
         installed_htons[db_type])
       return hton2plugin[installed_htons[db_type]->slot]->name.str;
-      return "*NONE*";
+    /* fall through */
+  case DB_TYPE_UNKNOWN:
+    return "UNKNOWN";
   }
 }
 
 
 static handler *create_default(TABLE_SHARE *table, MEM_ROOT *mem_root)
 {
-  handlerton *hton=ha_resolve_by_legacy_type(current_thd, DB_TYPE_DEFAULT);
+  handlerton *hton= ha_default_handlerton(current_thd);
   return (hton && hton->create) ? hton->create(table, mem_root) : NULL;
 }
 
@@ -152,10 +189,7 @@ handlerton *ha_resolve_by_legacy_type(THD *thd, enum legacy_db_type db_type)
 {
   switch (db_type) {
   case DB_TYPE_DEFAULT:
-    return (thd->variables.table_type != NULL) ?
-            thd->variables.table_type :
-            (global_system_variables.table_type != NULL ?
-             global_system_variables.table_type : &myisam_hton);
+    return ha_default_handlerton(thd);
   case DB_TYPE_UNKNOWN:
     return NULL;
   default:
@@ -196,7 +230,7 @@ handlerton *ha_checktype(THD *thd, enum legacy_db_type database_type,
     break;
   }
 
-  return ha_resolve_by_legacy_type(thd, DB_TYPE_DEFAULT);  
+  return ha_default_handlerton(thd);
 } /* ha_checktype */
 
 
diff --git a/sql/handler.h b/sql/handler.h
index f459d52fdeb..52843b78266 100644
--- a/sql/handler.h
+++ b/sql/handler.h
@@ -667,10 +667,6 @@ struct handlerton
                         struct handler_iterator *fill_this_in);
 };
 
-struct show_table_alias_st {
-  const char *alias;
-  enum legacy_db_type type;
-};
 
 /* Possible flags of a handlerton */
 #define HTON_NO_FLAGS                 0
@@ -1545,7 +1541,8 @@ extern ulong total_ha, total_ha_2pc;
 #define ha_rollback(thd) (ha_rollback_trans((thd), TRUE))
 
 /* lookups */
-handlerton *ha_resolve_by_name(THD *thd, LEX_STRING *name);
+handlerton *ha_default_handlerton(THD *thd);
+handlerton *ha_resolve_by_name(THD *thd, const LEX_STRING *name);
 handlerton *ha_resolve_by_legacy_type(THD *thd, enum legacy_db_type db_type);
 const char *ha_get_storage_engine(enum legacy_db_type db_type);
 handler *get_new_handler(TABLE_SHARE *share, MEM_ROOT *alloc,
diff --git a/sql/mysqld.cc b/sql/mysqld.cc
index dda2fbc3588..851c3111a79 100644
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -4984,11 +4984,12 @@ Disable with --skip-bdb (will save memory).",
    (gptr*) &default_collation_name, (gptr*) &default_collation_name,
    0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0 },
   {"default-storage-engine", OPT_STORAGE_ENGINE,
-   "Set the default storage engine (table type) for tables.", 0, 0,
+   "Set the default storage engine (table type) for tables.",
+   (gptr*)&default_storage_engine_str, (gptr*)&default_storage_engine_str,
    0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
   {"default-table-type", OPT_STORAGE_ENGINE,
    "(deprecated) Use --default-storage-engine.",
-   (gptr*)default_storage_engine_str, (gptr*)default_storage_engine_str,
+   (gptr*)&default_storage_engine_str, (gptr*)&default_storage_engine_str,
    0, GET_STR, REQUIRED_ARG, 0, 0, 0, 0, 0, 0},
   {"default-time-zone", OPT_DEFAULT_TIME_ZONE, "Set the default time zone.",
    (gptr*) &default_tz_name, (gptr*) &default_tz_name,
diff --git a/sql/sql_plugin.cc b/sql/sql_plugin.cc
index c15b484f448..f7205470abd 100644
--- a/sql/sql_plugin.cc
+++ b/sql/sql_plugin.cc
@@ -23,7 +23,7 @@ extern struct st_mysql_plugin *mysqld_builtins[];
 
 char *opt_plugin_dir_ptr;
 char opt_plugin_dir[FN_REFLEN];
-LEX_STRING plugin_type_names[MYSQL_MAX_PLUGIN_TYPE_NUM]=
+const LEX_STRING plugin_type_names[MYSQL_MAX_PLUGIN_TYPE_NUM]=
 {
   { (char *)STRING_WITH_LEN("UDF") },
   { (char *)STRING_WITH_LEN("STORAGE ENGINE") },
@@ -63,7 +63,7 @@ static HASH plugin_hash[MYSQL_MAX_PLUGIN_TYPE_NUM];
 static rw_lock_t THR_LOCK_plugin;
 static bool initialized= 0;
 
-static struct st_plugin_dl *plugin_dl_find(LEX_STRING *dl)
+static struct st_plugin_dl *plugin_dl_find(const LEX_STRING *dl)
 {
   uint i;
   DBUG_ENTER("plugin_dl_find");
@@ -112,7 +112,7 @@ static inline void free_plugin_mem(struct st_plugin_dl *p)
     my_free((gptr)p->plugins, MYF(MY_ALLOW_ZERO_PTR));
 }
 
-static st_plugin_dl *plugin_dl_add(LEX_STRING *dl, int report)
+static st_plugin_dl *plugin_dl_add(const LEX_STRING *dl, int report)
 {
 #ifdef HAVE_DLOPEN
   char dlpath[FN_REFLEN];
@@ -294,7 +294,7 @@ static st_plugin_dl *plugin_dl_add(LEX_STRING *dl, int report)
 }
 
 
-static void plugin_dl_del(LEX_STRING *dl)
+static void plugin_dl_del(const LEX_STRING *dl)
 {
 #ifdef HAVE_DLOPEN
   uint i;
@@ -322,7 +322,7 @@ static void plugin_dl_del(LEX_STRING *dl)
 }
 
 
-static struct st_plugin_int *plugin_find_internal(LEX_STRING *name, int type)
+static struct st_plugin_int *plugin_find_internal(const LEX_STRING *name, int type)
 {
   uint i;
   DBUG_ENTER("plugin_find_internal");
@@ -345,7 +345,7 @@ static struct st_plugin_int *plugin_find_internal(LEX_STRING *name, int type)
 }
 
 
-my_bool plugin_is_ready(LEX_STRING *name, int type)
+my_bool plugin_is_ready(const LEX_STRING *name, int type)
 {
   my_bool rc= FALSE;
   struct st_plugin_int *plugin;
@@ -359,7 +359,7 @@ my_bool plugin_is_ready(LEX_STRING *name, int type)
 }
 
 
-struct st_plugin_int *plugin_lock(LEX_STRING *name, int type)
+struct st_plugin_int *plugin_lock(const LEX_STRING *name, int type)
 {
   struct st_plugin_int *rc;
   DBUG_ENTER("plugin_lock");
@@ -396,7 +396,7 @@ static st_plugin_int *plugin_insert_or_reuse(struct st_plugin_int *plugin)
                               struct st_plugin_int *));
 }
 
-static my_bool plugin_add(LEX_STRING *name, LEX_STRING *dl, int report)
+static my_bool plugin_add(const LEX_STRING *name, const LEX_STRING *dl, int report)
 {
   struct st_plugin_int tmp;
   struct st_mysql_plugin *plugin;
@@ -479,7 +479,7 @@ err:
 }
 
 
-static void plugin_del(LEX_STRING *name)
+static void plugin_del(const LEX_STRING *name)
 {
   uint i;
   struct st_plugin_int *plugin;
@@ -811,7 +811,7 @@ void plugin_free(void)
 }
 
 
-my_bool mysql_install_plugin(THD *thd, LEX_STRING *name, LEX_STRING *dl)
+my_bool mysql_install_plugin(THD *thd, const LEX_STRING *name, const LEX_STRING *dl)
 {
   TABLE_LIST tables;
   TABLE *table;
@@ -866,7 +866,7 @@ err:
 }
 
 
-my_bool mysql_uninstall_plugin(THD *thd, LEX_STRING *name)
+my_bool mysql_uninstall_plugin(THD *thd, const LEX_STRING *name)
 {
   TABLE *table;
   TABLE_LIST tables;
diff --git a/sql/sql_plugin.h b/sql/sql_plugin.h
index b013beaba1f..df7c9a39495 100644
--- a/sql/sql_plugin.h
+++ b/sql/sql_plugin.h
@@ -66,15 +66,15 @@ typedef int (*plugin_type_init)(struct st_plugin_int *);
 
 extern char *opt_plugin_dir_ptr;
 extern char opt_plugin_dir[FN_REFLEN];
-extern LEX_STRING plugin_type_names[];
+extern const LEX_STRING plugin_type_names[];
 extern int plugin_init(void);
 extern void plugin_load(void);
 extern void plugin_free(void);
-extern my_bool plugin_is_ready(LEX_STRING *name, int type);
-extern st_plugin_int *plugin_lock(LEX_STRING *name, int type);
+extern my_bool plugin_is_ready(const LEX_STRING *name, int type);
+extern st_plugin_int *plugin_lock(const LEX_STRING *name, int type);
 extern void plugin_unlock(struct st_plugin_int *plugin);
-extern my_bool mysql_install_plugin(THD *thd, LEX_STRING *name, LEX_STRING *dl);
-extern my_bool mysql_uninstall_plugin(THD *thd, LEX_STRING *name);
+extern my_bool mysql_install_plugin(THD *thd, const LEX_STRING *name, const LEX_STRING *dl);
+extern my_bool mysql_uninstall_plugin(THD *thd, const LEX_STRING *name);
 
 extern my_bool plugin_register_builtin(struct st_mysql_plugin *plugin);
 
diff --git a/sql/sql_tablespace.cc b/sql/sql_tablespace.cc
index 94318a67575..13dfb491af4 100644
--- a/sql/sql_tablespace.cc
+++ b/sql/sql_tablespace.cc
@@ -30,7 +30,7 @@ int mysql_alter_tablespace(THD *thd, st_alter_tablespace *ts_info)
   */
   if (hton == NULL || hton->state != SHOW_OPTION_YES)
   {
-    hton= ha_resolve_by_legacy_type(thd, DB_TYPE_DEFAULT);
+    hton= ha_default_handlerton(thd);
     if (ts_info->storage_engine != 0)
       push_warning_printf(thd, MYSQL_ERROR::WARN_LEVEL_ERROR,
                           ER_WARN_USING_OTHER_HANDLER,