Package: django-query-profiler
This is a query profiler for Django applications, for helping developers answer the question “My Django code/page/API is slow, How do I find out why?”Below are some of the features of the profiler:Shows code paths making N+1 sql calls:  Shows the sql with stack_trace which is making N+1 calls, along with sql countShows the proposed solution: If the solution to reduce sql is to simply apply a select_related or a prefetch_related, this is highlighted as a suggestionShows exact sql duplicates: Count of the queries where (sql, parameters) is exactly the same.  This is the kind of sql where implementing a query cache would helpFlame Graph visualisation: Collects all the stack traces together to allow quickly identifying which area(s) of code is causing the load to the databaseCommand line or chrome plugin: The profiler can be called from command line via context manager, or can be invoked via a middleware, and output shown in a chrome pluginSuper easy to configure in any application:  The only changes are in settings.py file and in urls.py fileThis is therepofor the chrome pluginRequirementsThis works with any version of django >= 2.0, and running on python >= 3.6Profiler in Actionas a chrome pluginThis image shows how the chrome plugin would display profiled data, once it is configured & installedon command lineSee thisfilein the PR to see how to use the context manager, and how easy it is to find performance issues :-)The output of Django query profiler is same for the command line or the chrome plugin.   In fact, chrome plugin displays the output set by the middleware - which is just a plain wrapper around context manager.Getting StartedinstallationThe simplest way to getting started is to install the django query profiler from pip, and get the chrome plugin from
chrome web store.Python package:pip install django-query-profilerChrome Plugin:Download fromchrome webstoreThis is covered in detail in theinstallationsection in the docsconfiguration:This configuration is when we want to use the profiler along with the chrome plugin.  If we want to just use it on the
command line, the configuration is much more simpler (two lines of change to settings.py file) - that is covered in thedocssettings.py:fromdjango_query_profiler.settingsimport*INSTALLED_APPS=(...'django_query_profiler',...)MIDDLEWARE=(...# Request and all middleware that come after our middleware, would be profiled'django_query_profiler.client.middleware.QueryProfilerMiddleware',...)DATABASES=(...# Adding django_query_profiler as a prefix to your ENGINE setting# Assuming old ENGINE was "django.db.backends.sqlite3", this would be the new one"ENGINE":"django_query_profiler.django.db.backends.sqlite3",)urls.py:# Add this line to existing urls.pypath('django_query_profiler/',include('django_query_profiler.client.urls'))See thisPRon how to configure this in your application,
and how the plugin is going to look like after your configurationThis is covered in detail in theconfiguration instructionssection in the docsHow the profiler worksThis is also covered in detail in the documentation athow the profiler workssection in the docs,
along with how the code is organized.The docs also contain references to various links which helped us to lear about internals of Django, and to various projects which helped us to learn on how to add hooks when Django executes a queryChoosing Profiler levelsWe have two levels of profiler, and each of them have a different overhead.  The two levels are:QUERY_SIGNATURE:   This is the mode where we capture the query as well as the stack-trace.  This mode figures out the N+1 code paths and also tells us the proposed solutionQUERY: This is the mode where we just capture queries, and not the stack-traceOn an average, QUERY_SIGNATURE level adds an overhead of1 millisecond per 7 queries, and QUERY_SIGNATURE adds an overhead of1 millisecond per 25 queries.It is simple to change the profiler level for all the requests, or can be configured per request.  This is covered in thechoosing profiler levelsection of the docsCustomizing the profilerWe have tried to make the profiler customizable by providing hooks at various points.   Some of the use cases are covered
here in thecustomizing the defaultssection in docs.We plan to add more hooks for customizing the profiler as we gather more feedback from real world use cases.For contributorsThe django query profiler is released under the BSD license, like Django itself.If you like it, please consider contributing!  The docs cover everything from how to setup locally, to how the code is organized to running tests.DocumentationFull documentation is available atreadthedocs