speedup: indexes, caching

mixin.py

@@ -10,6 +10,7 @@ from trytond.modules.currency.ir import rate_decimal
 from trytond.transaction import Transaction
 from decimal import Decimal
 
+
 STATES = {
     'readonly': Or(
             Eval('state', '') != 'edit',
@@ -187,3 +188,18 @@ class SecondCurrencyMixin:
             return 2
 
 # end SecondCurrencyMixin
+
+
+class MemCacheIndexMx:
+    """ add index to 'create_date' + 'write_date'
+    """
+    @classmethod
+    def __setup__(cls):
+        super(MemCacheIndexMx, cls).__setup__()
+        # add index
+        cls.write_date.select = True
+        cls.create_date.select = True
+
+# end MemCacheIndexMx
+
+