Python modules for popular projects that add meta info to your SQL queries as comments.

• Django
• SQLAlchemy
• Psycopg2

pip3 install --user google-cloud-sqlcommenter

If you'd like to record some OpenCensus information as well, just install it:

pip3 install opencensus

Add the provided Django middleware to your Django project's settings. All queries executed within the standard request→response cycle will have the SQL comment prepended to them.

MIDDLEWARE = [
  'google.cloud.sqlcommenter.django.middleware.SqlCommenter',
  ...
]

which when viewed say on Postgresql logs, produces

2019-05-28 11:54:50.780 PDT [64128] LOG:  statement: INSERT INTO "polls_question"
("question_text", "pub_date") VALUES
('Wassup?', '2019-05-28T18:54:50.767481+00:00'::timestamptz) RETURNING
"polls_question"."id" /*controller='index',framework='django%3A2.2.1',route='%5Epolls/%24'*/

If you want the opencensus attributes included, you must set the SQLCOMMENTER_WITH_OPENCENSUS setting to True and include 'opencensus.ext.django.middleware.OpencensusMiddleware' before 'google.cloud.sqlcommenter.django.middleware.SqlCommenter', in your MIDDLEWARE setting.

Attach the provided event listener to the before_cursor_execute event of the database engine, with retval=True. All queries executed with that engine will have the SQL comment prepended to them.

import sqlalchemy
from google.cloud.sqlcommenter.sqlalchemy.executor import BeforeExecuteFactory

engine = sqlalchemy.create_engine(...)
listener = BeforeExecuteFactory(with_db_driver=True, with_db_framework=True, with_opencensus=True)
sqlalchemy.event.listen(engine, 'before_cursor_execute', listener, retval=True)
engine.execute(...) # comment will be added before execution

which will produce a backend log such as when viewed on Postgresql

2019-05-28 11:52:06.527 PDT [64087] LOG:  statement: SELECT * FROM polls_question
/*db_driver='psycopg2',framework='sqlalchemy%3A1.3.4',
traceparent='00-5bd66ef5095369c7b0d1f8f4bd33716a-c532cb4098ac3dd2-01',
tracestate='congo%%3Dt61rcWkgMzE%%2Crojo%%3D00f067aa0ba902b7'*/

Use the provided cursor factory to generate database cursors. All queries executed with such cursors will have the SQL comment prepended to them.

import psycopg2
from google.cloud.sqlcommenter.psycopg2.extension import CommenterCursorFactory

cursor_factory = CommenterCursorFactory(
    with_db_driver=True, with_dbapi_level=True, with_dbapi_threadsafety=True,
    with_driver_paramstyle=True, with_libpq_version=True, with_opencensus=True)
conn = psycopg2.connect(..., cursor_factory=cursor_factory)
cursor = conn.cursor()
cursor.execute(...) # comment will be added before execution

which will produce a backend log such as when viewed on Postgresql

2019-05-28 02:33:25.287 PDT [57302] LOG:  statement: SELECT * FROM
polls_question /*db_driver='psycopg2%%3A2.8.2%%20%%28dt%%20dec%%20pq3%%20ext%%20lo64%%29',
dbapi_level='2.0',dbapi_threadsafety=2,driver_paramstyle='pyformat',
libpq_version=100001,traceparent='00-5bd66ef5095369c7b0d1f8f4bd33716a-c532cb4098ac3dd2-01',
tracestate='congo%%3Dt61rcWkgMzE%%2Crojo%%3D00f067aa0ba902b7'*/

With Django, each option translates to a Django setting by uppercasing it and prepending SQLCOMMENTER_. For example, with_framework is controlled by the django setting SQLCOMMENTER_WITH_FRAMEWORK.

For opencensus to work correctly, note that:

• OpenCensus for Python must be installed in the python environment.
• Because the W3C TraceContext's traceparent and tracestate are quite ephemeral per request, including these attributes can have a negative impact on query caching.