Pilot for real-container testing of db_engine_specs against actual
databases (CockroachDB, CrateDB, Trino), via testcontainers-python.
Existing unit tests mock the driver/dialect layer entirely, which cannot
catch real SQL-compilation or type-mapping bugs -- e.g. #42899, where
Trino emitted OFFSET before LIMIT for paginated queries.
Runs nightly (.github/workflows/nightly-testcontainers.yml), not on every
merge: container pulls and startup are slower and more flake-prone than
the existing mocked unit tests, and this measures that cost/signal
tradeoff before considering wider adoption.
Building this surfaced two real bugs, fixed/documented separately:
- The cockroachdb dialect was completely broken under SQLAlchemy 2.0 due
to a dead upstream package -- fixed in #43501.
- testcontainers-python's TrinoContainer.get_connection_url() returns the
container-internal port instead of the Docker-mapped host port; worked
around locally, filed upstream.
