SQLAlchemy HawDB

sqlalchemy-hawdb provides a SQLAlchemy 2.x dialect for the embedded HawDB database. It uses HawDB's own PEP 249 driver and does not add a wire protocol or duplicate its DBAPI implementation.

Requirements

• Python 3.11 or newer
• HawDB Python binding 0.22.x (CI tests 0.22.0)
• SQLAlchemy 2.x

Install the dialect and its HawDB dependency from PyPI:

python -m pip install sqlalchemy-hawdb

To install this checkout instead:

python -m pip install /path/to/sqlalchemy_hawdb

Connect

Use an absolute database directory path with four slashes:

from sqlalchemy import Column, Integer, MetaData, String, Table, create_engine

engine = create_engine("hawdb:////var/lib/my-app/knowledge")
metadata = MetaData()
records = Table(
    "records",
    metadata,
    Column("id", Integer, primary_key=True, autoincrement=False),
    Column("body", String(500), nullable=False),
)

metadata.create_all(engine)
with engine.begin() as connection:
    connection.execute(records.insert(), {"id": 1, "body": "Hello HawDB"})

HawDB creates the database directory itself; its parent directory must already exist.

Use hawdb:///:memory: for an in-memory database. Like SQLAlchemy's SQLite dialect, the in-memory engine keeps one database per thread. Add ?read_only=true to open an existing database read-only.

HawDB connections are thread-affine and hold their database path until closed. For file databases the dialect uses SQLAlchemy's NullPool: each SQLAlchemy connection closes its HawDB handle when returned. Do not keep multiple connections to the same database path open at once or pass a SQLAlchemy connection between threads. In-memory connections are kept per thread and must also be used serially within that thread.

Supported behavior

• SQLAlchemy Core and ORM statements using HawDB's relational SQL subset
• Positional $1, $2, ... binding through HawDB's native DBAPI driver
• Explicit SQLAlchemy transactions mapped to HawDB commit and rollback
• Table, column, primary key, unique constraint, and index reflection from HawDB's information_schema and pg_catalog views
• The default public schema
• HawDB-native scalar DDL types: integer types map to BIGINT, floating and numeric types to DOUBLE PRECISION, strings to TEXT, and binary values to BYTEA; SQLAlchemy string lengths and numeric precision are not enforced by HawDB

HawDB does not report affected row counts, so DBAPI rowcount is -1 for statements without a result set. Date and time types compile to TEXT; their values are encoded and decoded by SQLAlchemy's standard processors. Auto-generated identity columns, sequences, schema alteration, savepoints, and concurrent connections to one database path are not supported by this initial dialect.

Development

Install the project, the HawDB dependency, and the test tools:

python -m pip install -e '.[test]'
python -m pytest

GitHub Actions builds the source distribution and wheel, checks their metadata, and tests the installed wheel against hawdb==0.22.0 from PyPI on Python 3.11-3.13 for every push and pull request. Missing HawDB wheels fail CI rather than skipping integration tests or falling back to a source build.

Publishing

.github/workflows/pypi.yaml publishes the tested source distribution and wheel when a GitHub Release is published. The release tag must match the version in pyproject.toml, for example v0.22.0. A manual workflow dispatch runs the same build and tests without uploading to PyPI.

Configure a PyPI Trusted Publisher for the sqlalchemy-hawdb project with:

• Owner: nowledge-co
• Repository: sqlalchemy-hawdb
• Workflow: pypi.yaml
• Environment: pypi

For the first release, configure a pending publisher in your PyPI account. The publish job uses GitHub's pypi environment and OIDC; no PyPI API token secret is required.