optimize discovery for cases when the storage engine is known in advance

sql/handler.cc

@@ -4162,6 +4162,8 @@ int ha_create_table(THD *thd, const char *path,
   else
   {
     // open an frm file
+    share.db_plugin= ha_lock_engine(thd, create_info->db_type);
+
     if (open_table_def(thd, &share))
       goto err;
   }
@@ -4343,12 +4345,17 @@ static my_bool discover_handlerton(THD *thd, plugin_ref plugin,
 int ha_discover_table(THD *thd, TABLE_SHARE *share)
 {
   DBUG_ENTER("ha_discover_table");
+  int found;
 
   DBUG_ASSERT(share->error == OPEN_FRM_OPEN_ERROR);   // share is not OK yet
-  DBUG_ASSERT(!share->db_plugin);
 
-  if (!plugin_foreach(thd, discover_handlerton,
-                      MYSQL_STORAGE_ENGINE_PLUGIN, share))
+  if (share->db_plugin)
+    found= discover_handlerton(thd, share->db_plugin, share);
+  else
+    found= plugin_foreach(thd, discover_handlerton,
+                        MYSQL_STORAGE_ENGINE_PLUGIN, share);
+  
+  if (!found)
     open_table_error(share, OPEN_FRM_OPEN_ERROR, ENOENT); // not found
 
   DBUG_RETURN(share->error != OPEN_FRM_OK);

sql/sql_base.cc

@@ -5908,6 +5908,8 @@ void close_tables_for_reopen(THD *thd, TABLE_LIST **tables,
   the opened TABLE instance will be addded to THD::temporary_tables list.
 
   @param thd                          Thread context.
+  @param hton                         Storage engine of the table, if known,
+                                      or NULL otherwise.
   @param path                         Path (without .frm)
   @param db                           Database name.
   @param table_name                   Table name.
@@ -5923,7 +5925,8 @@ void close_tables_for_reopen(THD *thd, TABLE_LIST **tables,
   @retval NULL on error.
 */
 
-TABLE *open_table_uncached(THD *thd, const char *path, const char *db,
+TABLE *open_table_uncached(THD *thd, handlerton *hton,
+                           const char *path, const char *db,
                            const char *table_name,
                            bool add_to_temporary_tables_list)
 {
@@ -5953,6 +5956,7 @@ TABLE *open_table_uncached(THD *thd, const char *path, const char *db,
 
   init_tmp_table_share(thd, share, saved_cache_key, key_length,
                        strend(saved_cache_key)+1, tmp_path);
+  share->db_plugin= ha_lock_engine(thd, hton);
 
   if (open_table_def(thd, share, GTS_TABLE | GTS_FORCE_DISCOVERY) ||
       open_table_from_share(thd, share, table_name,

sql/sql_base.h

@@ -195,8 +195,8 @@ bool open_new_frm(THD *thd, TABLE_SHARE *share, const char *alias,
 
 bool get_key_map_from_key_list(key_map *map, TABLE *table,
                                List<String> *index_list);
-TABLE *open_table_uncached(THD *thd, const char *path, const char *db,
-			   const char *table_name,
+TABLE *open_table_uncached(THD *thd, handlerton *hton, const char *path,
+                           const char *db, const char *table_name,
                            bool add_to_temporary_tables_list);
 TABLE *find_locked_table(TABLE *list, const char *db, const char *table_name);
 TABLE *find_write_locked_table(TABLE *list, const char *db,

sql/sql_partition.cc

@@ -4536,7 +4536,7 @@ uint prep_alter_part_table(THD *thd, TABLE *table, Alter_info *alter_info,
     */
     DBUG_ASSERT(thd->mdl_context.is_lock_owner(MDL_key::TABLE, db, table_name,
                                                MDL_INTENTION_EXCLUSIVE));
-    new_table= open_table_uncached(thd, path, db, table_name, 0);
+    new_table= open_table_uncached(thd, old_db_type, path, db, table_name, 0);
     if (!new_table)
       DBUG_RETURN(TRUE);
 

sql/sql_table.cc

@@ -2303,7 +2303,7 @@ int mysql_rm_table_no_locks(THD *thd, TABLE_LIST *tables, bool if_exists,
         Let's lock the plugin till the end of the statement.
       */
       if (table_type && table_type != view_pseudo_hton)
-        plugin_lock(thd, plugin_int_to_ref(hton2plugin[table_type->slot]));
+        ha_lock_engine(thd, table_type);
 
       if (thd->locked_tables_mode)
       {
@@ -4052,6 +4052,7 @@ static bool check_if_created_table_can_be_opened(THD *thd,
     return TRUE;
 
   init_tmp_table_share(thd, &share, db, 0, table_name, path);
+  share.db_plugin= ha_lock_engine(thd, file->ht);
 
   result= (open_table_def(thd, &share) ||
            open_table_from_share(thd, &share, "", 0, (uint) READ_ALL,
@@ -4401,7 +4402,7 @@ bool mysql_create_table_no_lock(THD *thd,
 
     /* prepare everything for discovery */
     share.field= &no_fields;
-    share.db_plugin= plugin_int_to_ref(hton2plugin[hton->slot]);
+    share.db_plugin= ha_lock_engine(thd, hton);
     share.option_list= create_info->option_list;
     share.connect_string= create_info->connect_string;
 
@@ -4435,7 +4436,8 @@ bool mysql_create_table_no_lock(THD *thd,
       THD::temporary_tables list.
     */
 
-    TABLE *table= open_table_uncached(thd, path, db, table_name, TRUE);
+    TABLE *table= open_table_uncached(thd, create_info->db_type, path,
+                                      db, table_name, TRUE);
 
     if (!table)
     {
@@ -6779,7 +6781,8 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
       build_table_filename(path, sizeof(path) - 1, new_db, tmp_name, "",
                            FN_IS_TMP);
       /* Open our intermediate table. */
-      new_table= open_table_uncached(thd, path, new_db, tmp_name, TRUE);
+      new_table= open_table_uncached(thd, new_db_type, path,
+                                     new_db, tmp_name, TRUE);
     }
     if (!new_table)
       goto err_new_table_cleanup;

sql/sql_truncate.cc

@@ -269,7 +269,7 @@ static bool recreate_temporary_table(THD *thd, TABLE *table)
   dd_recreate_table(thd, share->db.str, share->table_name.str,
                     share->normalized_path.str);
 
-  if (open_table_uncached(thd, share->path.str, share->db.str,
+  if (open_table_uncached(thd, table_type, share->path.str, share->db.str,
                           share->table_name.str, TRUE))
   {
     error= FALSE;

sql/table.cc

@@ -1101,10 +1101,7 @@ int TABLE_SHARE::init_from_binary_frm_image(THD *thd, bool write,
       plugin_ref tmp_plugin= ha_resolve_by_name(thd, &name);
       if (tmp_plugin != NULL && !plugin_equals(tmp_plugin, se_plugin))
       {
-        if (legacy_db_type > DB_TYPE_UNKNOWN &&
-            legacy_db_type < DB_TYPE_FIRST_DYNAMIC &&
-            legacy_db_type != ha_legacy_type(
-                plugin_data(tmp_plugin, handlerton *)))
+        if (se_plugin)
         {
           /* bad file, legacy_db_type did not match the name */
           goto err;
@@ -1236,6 +1233,9 @@ int TABLE_SHARE::init_from_binary_frm_image(THD *thd, bool write,
   }
   share->key_block_size= uint2korr(frm_image+62);
 
+  if (share->db_plugin && !plugin_equals(share->db_plugin, se_plugin))
+    goto err; // wrong engine (someone changed the frm under our feet?)
+
   extra_rec_buf_length= uint2korr(frm_image+59);
   rec_buff_length= ALIGN_SIZE(share->reclength + 1 + extra_rec_buf_length);
   share->rec_buff_length= rec_buff_length;
@@ -1955,7 +1955,6 @@ int TABLE_SHARE::init_from_binary_frm_image(THD *thd, bool write,
     (void) my_hash_check(&share->name_hash);
 #endif
 
-  DBUG_ASSERT(!share->db_plugin || plugin_equals(share->db_plugin, se_plugin));
   share->db_plugin= se_plugin;
   share->error= OPEN_FRM_OK;
   thd->status_var.opened_shares++;