Debugging ORM queries with database logs

When developing with an ORM, I often find it helpful to check the generated SQL code.
It helps notice and fix 'N+1' query issues, or just confirm the ORM produced the intended query.

ORMs often provide logging options, like SQLAlchemy's echo=True flag.

Here's a sample SQLAlchemy log:

INFO:sqlalchemy.engine.Engine:SELECT api.company_source.company_identity_id AS api_company_source_company_identity_id, api.company_source.name AS api_company_source_name
FROM api.company_source
WHERE api.company_source.company_identity_id IN (%(primary_keys_1)s, %(primary_keys_2)s, %(primary_keys_3)s, %(primary_keys_4)s, %(primary_keys_5)s, %(primary_keys_6)s, %(primary_keys_7)s, %(primary_keys_8)s, %(primary_keys_9)s, %(primary_keys_10)s)
INFO:sqlalchemy.engine.Engine:[generated in 0.00011s] {'primary_keys_1': 1, 'primary_keys_2': 2, 'primary_keys_3': 3, 'primary_keys_4': 4, 'primary_keys_5': 5, 'primary_keys_6': 6, 'primary_keys_7': 7, 'primary_keys_8': 8, 'primary_keys_9': 9, 'primary_keys_10': 10}

I used these regularly until I realized we can get the logs directly from the database.
Now I simply use (here from a docker compose config):

db:
  image: postgres:17
  command: ["postgres", "-c", "log_statement=all"]

This logs all queries to stdout, producing something like¹:

db-1       | 2025-02-27 15:51:16.912 UTC [85] LOG:  statement: SELECT api.company_source.company_identity_
id AS api_company_source_company_identity_id, api.company_source.name AS api_company_source_name
db-1       | 	FROM api.company_source
db-1       | 	WHERE api.company_source.company_identity_id IN (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)

Why I like this more than echo=True:

• It works with any ORM, or no ORM at all.
• I can keep it on all the time, it won't drown out useful application logs.
• It makes copy-pasting queries into a SQL console much easier.
• There are useful variants too: ["postgres", "-c", "log_min_duration_statement=0"] logs all queries and their durations.

I find this a practical tool for development, and a great 'first-line' debugging tool.
It's also a nice learning tool for developers who want to understand exactly how the ORM fetches data.