sqldjangoperformancedjango-modelsbacktrace

How to see the traceback for each Django query?


I want a traceback from every query executed during a request, so I can find where they're coming from and reduce the count/complexity.

I'm using this excellent snippet of middleware to list and time queries, but I don't know where in the they're coming from.

I've poked around in django/db/models/sql/compiler.py but apparent form getting a local version of django and editing that code I can't see how to latch on to queries. Is there a signal I can use? it seems like there isn't a signal on every query.

Is it possible to specify the default Manager?

(I know about django-toolbar, I'm hoping there's a solution without using it.)


Solution

  • An ugly but effective solution (eg. it prints the trace on all queries and only requires one edit) is to add the following to the bottom of settings.py:

    import django.db.backends.utils as bakutils
    import traceback
    
    bakutils.CursorDebugWrapper_orig = bakutils.CursorWrapper
    
    def print_stack_in_project():
        stack = traceback.extract_stack()
        for path, lineno, func, line in stack:
            if 'lib/python' in path or 'settings.py' in path:
                continue
            print 'File "%s", line %d, in %s' % (path, lineno, func)
            print '  %s' % line
    
    class CursorDebugWrapperLoud(bakutils.CursorDebugWrapper_orig):
        def execute(self, sql, params=None):
            try:
                return super(CursorDebugWrapperLoud, self).execute(sql, params)
            finally:
                print_stack_in_project()
                print sql
                print '\n\n\n'
    
        def executemany(self, sql, param_list):
            try:
                return super(CursorDebugWrapperLoud, self).executemany(sql, param_list)
            finally:
                print_stack_in_project()
                print sql
                print '\n\n\n'
    
    bakutils.CursorDebugWrapper = CursorDebugWrapperLoud
    

    Still not sure if there is a more elegant way of doing this?