Deferred Counters

Deferred Counters is a Django app that allows to count things and keet a queue of pending counts increments or decrements to avoid locking. Then you can compact the queue applying the pending changes.

A Deferred Counter has a value "current_value" that has the counter value since the last time it was compacted.

You can call compute_value() to get the value of the counter considering the changes that have not yet been applied.

Also, it offers a manager with "with_computed_value" that add the field computed_value to the query set.

More information of the problem this app resolves and how it solves it can be read here: https://www.depesz.com/2016/06/14/incrementing-counters-in-database/

Quick start

1. Add "deferredCounters" to your INSTALLED_APPS setting like this:

   INSTALLED_APPS = [
       ...
       'deferredCounters',
   ]
   

2. Run python manage.py migrate to create the Deferred Counters models.

3. Use it in your models with a foreign key to Deferred Counter.