diff options
| author | Tom Forbes <tom@tomforb.es> | 2018-08-18 14:22:21 +0100 |
|---|---|---|
| committer | Tim Graham <timograham@gmail.com> | 2018-08-18 09:23:03 -0400 |
| commit | 77498db196fede2cb4dbee9e7cd7762a99c5ded8 (patch) | |
| tree | ab811f797dd8cae0a21ad4242818feb411260dd5 | |
| parent | cae84904c6a5facc0edd75e030c775de437320e0 (diff) | |
[2.1.x] Fixed #29685 -- Added QuerySet.explain() to the database optimization docs.
Backport of b042ab897636987701d3a35d6b566c6bef9d6ea2 from master
| -rw-r--r-- | docs/topics/db/optimization.txt | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/docs/topics/db/optimization.txt b/docs/topics/db/optimization.txt index 96ff65fd7e..dad68f58af 100644 --- a/docs/topics/db/optimization.txt +++ b/docs/topics/db/optimization.txt @@ -11,8 +11,9 @@ Profile first ============= As general programming practice, this goes without saying. Find out :ref:`what -queries you are doing and what they are costing you -<faq-see-raw-sql-queries>`. You may also want to use an external project like +queries you are doing and what they are costing you <faq-see-raw-sql-queries>`. +Use :meth:`.QuerySet.explain` to understand how specific ``QuerySet``\s are +executed by your database. You may also want to use an external project like django-debug-toolbar_, or a tool that monitors your database directly. Remember that you may be optimizing for speed or memory or both, depending on @@ -114,6 +115,14 @@ When you have a lot of objects, the caching behavior of the ``QuerySet`` can cause a large amount of memory to be used. In this case, :meth:`~django.db.models.query.QuerySet.iterator()` may help. +Use ``explain()`` +----------------- + +:meth:`.QuerySet.explain` gives you detailed information about how the database +executes a query, including indexes and joins that are used. These details may +help you find queries that could be rewritten more efficiently, or identify +indexes that could be added to improve performance. + Do database work in the database rather than in Python ====================================================== |