refs #5554, merge handlerton piece

git-svn-id: file:///svn/mysql/tokudb-engine/tokudb-engine@52114 c7de825b-a66e-492c-adef-691d508d4ae1

storage/tokudb/ha_tokudb.cc

@@ -5885,6 +5885,9 @@ int ha_tokudb::create_txn(THD* thd, tokudb_trx_data* trx) {
         if (txn_begin_flags == 0 && is_autocommit && thd_sql_command(thd) == SQLCOM_SELECT) {
             txn_begin_flags = DB_TXN_SNAPSHOT;
         }
+        if (is_autocommit && thd_sql_command(thd) == SQLCOM_SELECT && !thd->in_sub_stmt) {
+            txn_begin_flags |= DB_TXN_READ_ONLY;
+        }
     }
     else {
         txn_begin_flags = DB_INHERIT_ISOLATION;