Support for psycopg Composed queries

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#749 5 comments 0 reactions 0 assignees View on GitHub

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
45/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Stale
Tech stack
django, postgresql, python
Domain
backend, databases, observability

Research direction

Start at src/scout_apm/core/n_plus_one_tracker.py line 29 and reproduce the Django raw-query failure with psycopg2 SQL composition. Trace how the Composed query reaches the instrumentation code; done means the query is instrumented without the TypeError or the workaround that converts it to a string.

Written by the indexing model from the issue text.

Description

The Scout agent breaks when it tries to instrument raw queries in Django that use psycopg2's SQL string composition. Specifically, we get a TypeError: unhashable type: 'Composed' on this line of code:

https://github.com/scoutapp/scout_apm_python/blob/86d14920a59a7a3b5dfffe680586646ee29bdd7a/src/scout_apm/core/n_plus_one_tracker.py#L29

I created a workaround that converts the query to a raw string before executing it, however it involves getting a cursor and compiling the string before doing the actual query. That's more overhead than I would prefer, so it would be really nice if Scout were able to support Composed as well.

Dominant language
Python
Stars
77
Forks
19
Avg merge
1d 9h
Merged PRs (30d)
5

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