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Fetching list of SQL queries executed so far for all requests

Author:
hiddentao
Posted:
December 18, 2011
Language:
Python
Version:
1.3
Score:
3 (after 3 ratings)

These snippets together give you the ability to view all Django SQL queries executed across all incoming requests by visiting a particular URL (/profiling in the example). This is useful when developing with the Django test server.

This is useful if most of the incoming requests are AJAX requests, because in such cases the debug toolbar will not be able to show which queries got executed.

The SqlProfilingMiddleware class is the key one. At the end of every incoming request it appends the executed SQL queries to a static class member list. Any information request profiling information can be added in this way.

The snippet does not add any security around viewing such information. This was done just to keep the code simple. But when implementing this you will definitely want to restrict access to this URL to only people allowed to view such information.

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# file: settings.py

MIDDLEWARE_CLASSES = (
    'django.middleware.common.CommonMiddleware',
    'yourapp.middleware.SqlProfilingMiddleware',
    ...
)



# file: yourapp/midddlware.py

from django.db import connection
import time

class SqlProfilingMiddleware(object):
    Queries = []

    def process_request(self, request):
        return None
    def process_view(self, request, view_func, view_args, view_kwargs):
        return None
    def process_template_response(self, request, response):
        self._add_sql_queries(request)
        return response
    def process_response(self, request, response):
        self._add_sql_queries(request)
        return response
    def process_exception(self, request, exception):
        return None

    def _add_sql_queries(self, request):
        for q in connection.queries:
            q["time"] = time.time() + float(q["time"])
            SqlProfilingMiddleware.Queries.insert(0, q)
            # add request info as a separator
        SqlProfilingMiddleware.Queries.insert(0, {"time": time.time(), "path" : request.path})



# file: yourapp/views.py

from yourapp.middleware import SqlProfilingMiddleware

def profiling(request):
    return render_to_response("profiling.html", {"queries": SqlProfilingMiddleware.Queries})



# file: urls.py

urlpatterns = patterns('',
  (r'^profiling/$', 'yourapp.views.profiling'),
)



# file: yourapp/templates/profiling.html


        <div id="profiling">
            <h2>SQL queries</h2>
            <table cellpadding="0" cellspacing="0">
                <thead>
                    <tr>
                       <th>Time</th>
                       <th>SQL</th>
                    </tr>
                </thead>
                <tbody>
                {% for q in queries %}
                    {% if q.path %}
                    <tr class="path">
                        <td >{{ q.time }}</td>
                        <td>{{ q.path }}</td>
                    </tr>
                    {% else %}
                    <tr class="sql">
                        <td >{{ q.time }}</td>
                        <td>{{ q.sql }}</td>
                    </tr>
                    {% endif %}
                {% endfor %}
                </tbody>
            </table>
        </div>

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Comments

aisbaa (on December 18, 2011):

This snippet could be great app.

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