For issue:

noripyt#135

Have the table key generation look for a "CACHE_KEY" configuration in the Django DATABASES configs.

If a "CACHE_KEY" value is found, then we use that instead of the "db_alias".

This allows us to synch Master and Replicas to use the same key namespace to prevent "double-caching" and the need to invalidate 2 cache entries upon an update.

The Django configuration would look like:

DATABASES = {
    'master': {
        'CACHE_KEY': 'WE_ARE_ONE',
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': DB_NAME,
        'USER': DB_USER,
        'PASSWORD': DB_PASSWORD,
        'HOST': DB_HOST,
        'PORT': DB_PORT,
        'OPTIONS': {
            'client_encoding': "UTF8"
        }
    },
    'replica' : {
        'CACHE_KEY': 'WE_ARE_ONE',
        'ENGINE': 'django.db.backends.postgresql_psycopg2',
        'NAME': DB_NAME,
        'USER': DB_USER,
        'PASSWORD': DB_PASSWORD,
        'HOST': DB_HOST,
        'PORT': DB_PORT,
        'OPTIONS': {
            'client_encoding': "UTF8"
        }
    }
}

cachalot/utils.py

@@ -33,6 +33,7 @@ class IsRawQuery(Exception):
 }
 CACHABLE_PARAM_TYPES.update(integer_types)  # Adds long for Python 2
 UNCACHABLE_FUNCS = {Now, TransactionNow}
+OVERRIDE_DB_ALIAS_KEY = 'CACHE_KEY'
 
 try:
     from psycopg2 import Binary
@@ -91,6 +92,8 @@ def get_table_cache_key(db_alias, table):
     :return: A cache key
     :rtype: int
     """
+    if OVERRIDE_DB_ALIAS_KEY in cachalot_settings.DATABASES[db_alias]:
+        db_alias = cachalot_settings.DATABASES[db_alias][OVERRIDE_DB_ALIAS_KEY]
     cache_key = '%s:%s' % (db_alias, table)
     return sha1(cache_key.encode('utf-8')).hexdigest()