Indexes

[minsau]

Hello! I succesfully integrate the library is great! But When it was used in a semi-prod environment, it elevates the cpu usage, and it was because when you look for the notifications use channel and payload as filters, those fields has no indexes due to that the queries are realy low.

So, adding a multi-field index, do the trick for us.
You can considere add it as main part

[PaulGilmartin]

@minsau that's a good suggestion and I can see how that could make a great improvement to the performance of the query

            Notification.objects.select_for_update(
                skip_locked=True).filter(
                channel=self.notification.channel,
                payload=self.notification.payload,
            )

I will try to add that in the next version of this library. Perhaps however the index should be optional, since adding an index on an already large/active table can sometimes be tricky in production.

Feel free to share the code you added or submit a pull request with the proposed change, otherwise I will look at it whenever I have time :)