Use exists query instead of count in clean-duplicate-history command. (#1015)

* Use exists query instead of count in clean-duplicate_history command.

* Improved changelog for #1015

---------

Co-authored-by: Anders <6058745+ddabble@users.noreply.github.com>

Author: Anton

AUTHORS.rst

@@ -16,6 +16,7 @@ Authors
 - Alexander Anikeev
 - Amanda Ng (`AmandaCLNg <https://github.com/AmandaCLNg>`_)
 - Amartis Gladius (`Amartis <https://github.com/amartis>`_)
+- Anton Kulikov (`bigtimecriminal <https://github.com/bigtimecriminal>`_)
 - Ben Lawson (`blawson <https://github.com/blawson>`_)
 - Benjamin Mampaey (`bmampaey <https://github.com/bmampaey>`_)
 - Bheesham Persaud (`bheesham <https://github.com/bheesham>`_)

CHANGES.rst

@@ -14,6 +14,7 @@ Unreleased
   now allowed; history records will still be created (gh-1248)
 - Added temporary requirement on ``asgiref>=3.6`` while the minimum required Django
   version is lower than 4.2 (gh-1261)
+- Small performance optimization of the ``clean-duplicate_history`` command (gh-1015)
 
 3.4.0 (2023-08-18)
 ------------------

simple_history/management/commands/clean_duplicate_history.py

@@ -74,9 +74,10 @@ def _process(self, to_process, date_back=None, dry_run=True):
             m_qs = history_model.objects
             if stop_date:
                 m_qs = m_qs.filter(history_date__gte=stop_date)
-            found = m_qs.count()
-            self.log(f"{model} has {found} historical entries", 2)
-            if not found:
+            if self.verbosity >= 2:
+                found = m_qs.count()
+                self.log(f"{model} has {found} historical entries", 2)
+            if not m_qs.exists():
                 continue
 
             # Break apart the query so we can add additional filtering