Currently, two calls can raise exceptions in the _trace_callback() in Modules/_sqlite/connection.c:

  1. PyUnicode_DecodeUTF8() can raise an exception
  2. PyObject_CallOneArg() — calling the user callback — can raise an exception

Currently, we either PyErr_Print() the traceback, or we PyErr_Clear() it. In either case; we clear the current exception. The other SQLite callbacks pass some kind of return value back to SQLite to indicate failure (which is normally then passed to _pysqlite_seterror() via sqlite3_step() or sqlite3_finalize(), but the trace callback does not pass errors back to SQLite; we're unable to detect if the trace callback fails.

Quoting Petr from PR 28133:
  Without the ability to tell SQLite to abort on trace failure, I doubt we can
  do much better than the current behavior. Getting an exception and having
  the data inserted seems quite irregular.


Closing this issue as won't fix.

It *would* be possible to improve the documentation, though.
Say that it is only meant for debugging, document that exceptions are not propagated, and mention enable_callback_tracebacks.

> It *would* be possible to improve the documentation, though.

+1

New changeset 51056b40e711d84692d099ac8970077b33c7fafd by Erlend Egeberg Aasland in branch 'main':
bpo-45089: Improve sqlite3 trace callback docs (GH-28238)
https://github.com/python/cpython/commit/51056b40e711d84692d099ac8970077b33c7fafd

New changeset 87f0ac8c1de83ac63447b9fe799dfb1657a5a9db by Miss Islington (bot) in branch '3.10':
bpo-45089: Improve sqlite3 trace callback docs (GH-28238) (GH-28371)
https://github.com/python/cpython/commit/87f0ac8c1de83ac63447b9fe799dfb1657a5a9db

New changeset 97802a8edb3f15aef9ecc1cac97c4c1b4ed3fdfc by Miss Islington (bot) in branch '3.9':
bpo-45089: Improve sqlite3 trace callback docs (GH-28238) (GH-28372)
https://github.com/python/cpython/commit/97802a8edb3f15aef9ecc1cac97c4c1b4ed3fdfc

Thanks, Erlend! ✨ 🍰 ✨

New changeset 6fc66d6b9d39fa7a5a8692062d54b5a6a1aa0283 by Pablo Galindo (Miss Islington (bot)) in branch '3.10':
bpo-45089: Improve sqlite3 trace callback docs (GH-28238) (GH-28371)
https://github.com/python/cpython/commit/6fc66d6b9d39fa7a5a8692062d54b5a6a1aa0283