diff --git a/roles/db/files/conf/z90-vn.cnf b/roles/db/files/conf/z90-vn.cnf
index 0c77ad2..6856ddd 100644
--- a/roles/db/files/conf/z90-vn.cnf
+++ b/roles/db/files/conf/z90-vn.cnf
@@ -34,7 +34,7 @@ table_open_cache                            = 50000
 table_definition_cache                      = 10000
 table_open_cache_instances                  = 1
 key_buffer_size                             = 256K
-max_heap_table_size                         = 128M
+max_heap_table_size                         = 512M
 tmp_table_size                              = 128M
 concurrent_insert                           = ALWAYS
 group_concat_max_len                        = 10000