SQLite is the local baseline for all ORM behavior tests.
PostgreSQL, MySQL, MariaDB, SQL Server, and Oracle have gated Rust integration tests that run when their ORMDANTIC_*_URL variables are set.
SQL Server and Oracle runtimes are available behind optional Cargo features for source builds because they add larger enterprise-driver dependencies; default Python extension builds include them.
The dialect layer exposes backend bind-parameter limits, query compilation rejects oversized parameter sets before runtime execution, and select-in relationship loaders cap batches to the active backend limit.
Runtime execution errors carry structured categories for common connection, syntax, constraint, transaction-conflict, timeout, and permission failures while preserving stable display messages.
Live migration autogenerate reflects core table metadata across SQLite, PostgreSQL, MySQL, MariaDB, SQL Server, and Oracle, including schema-scoped table snapshots on schema-aware backends.
docker/databases/ provides a local Compose matrix for PostgreSQL, MySQL, MariaDB, SQL Server, and Oracle, plus a runner for the external migration smoke tests, relationship-loader stress suite, live autogenerate checks, and Rust engine tests.