Adding a prefix to cache keys

[Andrew-Chen-Wang]

@Andrew-Chen-Wang

Could you point me where code I need to patch to achieve "adding a prefix to cache keys"?
https://github.com/Suor/django-cacheops#sharing-redis-instance

The main goal to add a prefix by hostname Thanks

Originally posted by @abodacs in #164 (comment)

All our cache keys are hashed with sha1 so there's really no chance of collision. If you really want to add a prefix, in your Django settings, you have a "CACHES" dictionary. Then create a new key called "cachalot" (or whatever you want the cache to be called) and it should have the same values (i.e. host, parser, etc.) as your "default" cache. Then set CACHALOT_CACHE to "cachalot" or whatever you previously called your cache.

[Andrew-Chen-Wang]

This issue was for @abodacs

[abodacs]

@Andrew-Chen-Wang

I think what was proposed at https://github.com/Suor/django-cacheops#sharing-redis-instance is to allow multi-tenancy, Is it possible at django-cachalot?

[Andrew-Chen-Wang]

@abodacs before I give the solution, I'm not entirely sure if adding a prefix to the generated cache key is really necessary (I guess it's helpful for invalidating caches manually) since we use sha1. But in any case, it is entirely possible. You just need to make your own functions and use our settings to point to those functions:

from cachalot.utils import get_query_cache_key, get_table_cache_key

def custom_get_query_cache_key(compiler):
    return "prefix" + get_query_cache_key(compiler)

def custom_get_table_cache_key(db_alias, table):
    return "prefix" + get_table_cache_key(db_alias, table)

You can then use these settings: https://django-cachalot.readthedocs.io/en/latest/quickstart.html#cachalot-query-keygen, just add:

CACHALOT_QUERY_KEYGEN = "path.to.module.custom_get_query_cache_key"
CACHALOT_TABLE_KEYGEN = "path.to.module.custom_get_table_cache_key"

Hope that helps!

Edit: if you're just going to hardcode a prefix, for compatibility sake if you don't use tests in Django, then you can write:

def custom_get_query_cache_key(*args, **kwargs):
    return "prefix" + get_query_cache_key(*args, **kwargs)

def custom_get_table_cache_key(*args, **kwargs):
    return "prefix" + get_table_cache_key(*args, **kwargs)

[abodacs]

Thanks, 💕
I'll try this