diff --git a/optuna/storages/_rdb/models.py b/optuna/storages/_rdb/models.py
index 869b390ddd..d175a610d9 100644
--- a/optuna/storages/_rdb/models.py
+++ b/optuna/storages/_rdb/models.py
@@ -28,7 +28,6 @@
 SCHEMA_VERSION = 12
 
 MAX_INDEXED_STRING_LENGTH = 512
-MAX_STRING_LENGTH = 2048
 MAX_VERSION_LENGTH = 256
 
 NOT_FOUND_MSG = "Record does not exist."