From f05b143e4c1e3f9e9bb4897274ec35fd44ef3457 Mon Sep 17 00:00:00 2001
From: Bertrand Bordage <bordage.bertrand@gmail.com>
Date: Sun, 4 Oct 2015 21:02:10 +0200
Subject: [PATCH] Tiny optimisation.

---
 cachalot/utils.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/cachalot/utils.py b/cachalot/utils.py
index 2ef5299..df0c75f 100644
--- a/cachalot/utils.py
+++ b/cachalot/utils.py
@@ -19,10 +19,10 @@ class UncachableQuery(Exception):
     pass
 
 
-CACHABLE_PARAM_TYPES = (
+CACHABLE_PARAM_TYPES = frozenset((
     bool, int, binary_type, text_type, type(None),
     datetime.date, datetime.time, datetime.datetime, datetime.timedelta
-)
+))
 
 def get_query_cache_key(compiler):
     """