diff --git a/config-example.toml b/config-example.toml
index 424417a..47a5947 100644
--- a/config-example.toml
+++ b/config-example.toml
@@ -113,4 +113,4 @@ max_idle_timeout = 10              # secs. 0 represents an infinite timeout.
 cache_dir = './cache'               # optional. default is "./cache" relative to the current working directory
 max_cache_entry = 1000              # optional. default is 1k
 max_cache_each_size = 65535         # optional. default is 64k
-max_cache_each_size_onmemory = 4096 # optional. default is 4k
+max_cache_each_size_onmemory = 4096 # optional. default is 4k if 0, it is always file cache.