A faster version of the default Django Paginator

accellerated_django_paginator.py

# This is an improved Django Paginator that makes Admin list view pages load much faster.

# You can tell if you need this if you see a big slow COUNT() query
# in the django_debug_toolbar SQL panel on every admin list view.

# It improves performance by avoiding running a potentially costly DISTINCT query to
# count total rows on every pageload. Instead, when possible (when there are no filters)
# it does a significantly simpler SELECT COUNT(*) tablename to get the total.

from django.core.paginator import Paginator
from django.utils.functional import cached_property

class AccelleratedPaginator(Paginator):
    """
    Accellerated Pagniator ignores DISTINCT when counting total number of rows.
    Speeds up SELECT Count(*) on Admin views by >20x.
    https://hakibenita.com/optimizing-the-django-admin-paginator
    """

    @cached_property
    def count(self):
        if self.object_list._has_filters():
            # fallback to normal count method on filtered queryset
            return super().count

        # otherwise count total rows in a separate fast query
        return self.object_list.model.objects.count()

        # Alternative approach for PostgreSQL: fallback if count takes > 200ms
        # from django.db import connection, transaction, OperationalError
        # with transaction.atomic(), connection.cursor() as cursor:
        #     cursor.execute('SET LOCAL statement_timeout TO 200;')
        #     try:
        #         # try potentially slow count query, gets interrupted if it takes too long
        #         return super().count
        #     except OperationalError:
        #         # fallback to a faster but less accurate count (just returns total object of this type, without any costly filters)
        #         return self.object_list.model.objects.count()


# USAGE:
from django.contrib import admin

@admin.register(SomeModel)
class SomeModelAdmin(admin.ModelAdmin):
    ...
    paginator = AccelleratedPaginator