Skip to main content

PostgreSQL client for Trio based on asyncpg

Project description

Automated test status (Linux and MacOS) Automated test status (Windows) Test coverage


Welcome to triopg!

PostgreSQL client for Trio based on asyncpg.

License: Your choice of MIT or Apache License 2.0

Quick example:

import trio_asyncio
import triopg

async def main():
    async with triopg.connect() as conn:

        await conn.execute(
            DROP TABLE IF EXISTS users;
            CREATE TABLE IF NOT EXISTS users (
                _id SERIAL PRIMARY KEY,
                user_id VARCHAR(32) UNIQUE

        async with conn.transaction():
            await conn.execute("INSERT INTO users (user_id) VALUES (1)")
            await conn.execute("INSERT INTO users (user_id) VALUES (2)")
            await conn.execute("INSERT INTO users (user_id) VALUES (3)")

        print(await conn.fetch("SELECT * FROM users"))

API basics

triopg is a thin Trio-compatible wrapper around asyncpg. The API is the same, with one exception - triopg does not support manual resource management. In asyncpg you can manage pools, connections and transactions manually:

conn = await asyncpg.connect()
tr = conn.transaction()
# ..

While in triopg you can only use async with blocks:

async with triopg.connect() as conn:
    async with conn.transaction():
        # ...

Otherwise you can follow asyncpg tutorial and reference. Everything should work the same way. Please file an issue if it doesn’t.


In addition to asyncpg-compatible API, triopg provides Trio-style .listen() helper for the eponymous Postgres statement:

async with conn.listen('', max_buffer_size=1) as notifications:
    async for notification in notifications:
        if notification != triopg.NOTIFY_OVERFLOW:
            print('Notification received:', notification)

max_buffer_size is the amount of notifications you are willing to queue in memory.

If you don’t want to think about buffering, set the buffer size to math.inf and everything will just work in regular non-pathological situations.

Otherwise, you can set a finite buffer. In this case you should handle triopg.NOTIFY_OVERFLOW marker and react according to your use case. For example, you could re-scan the tables, like you would do at startup. Or could you simply ignore the marker if you are only interested in the newest notifications.

For detailed discussion on buffering, see Trio manual, “Buffering in channels” section.

Note: we can’t politely ask Postgres to slow down: LISTEN backpressure is not supported by asyncpg. There’s also an inherent challenge with Postgres. Postgres (like most broadcast systems) doesn’t really have a good way to communicate backpressure further upstream to the clients that are calling NOTIFY.

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

triopg-0.6.0.tar.gz (19.7 kB view hashes)

Uploaded source

Built Distribution

triopg-0.6.0-py3-none-any.whl (13.8 kB view hashes)

Uploaded py3

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page