Connection Pool Adapters¶

PostgresCache doesn’t open connections itself. It needs an implementation for the psycache.typing.CachePool Protocol: anything with a connect() context manager that yields a psycopg.Connection.

The shipped pool adapters are optional and each lives behind a packaging extra; the cache itself needs only psycopg.

Pick the one that matches the infrastructure you already have.

SQLAlchemy¶

SQLAlchemyCachePool wraps a SQLAlchemy Engine (requires psycache[sqlalchemy]). This lets the cache ride on the very same engine – and therefore the same pool – that the rest of your application already uses:

from sqlalchemy import create_engine

from psycache import PostgresCache
from psycache.sqlalchemy import SQLAlchemyCachePool


engine = create_engine("postgresql+psycopg://psycache@127.0.0.1/psycache")
cache = PostgresCache(SQLAlchemyCachePool(engine))

engine.dispose()

psycopg-pool¶

PsycopgCachePool wraps a psycopg_pool.ConnectionPool (requires psycache[pool]):

from psycopg_pool import ConnectionPool

from psycache import PostgresCache
from psycache.psycopg_pool import PsycopgCachePool


with ConnectionPool(
    "postgresql://psycache@127.0.0.1/psycache", open=False
) as pool:
    cache = PostgresCache(PsycopgCachePool(pool))

Your own pool¶

If neither adapter fits, implement the psycache.typing.CachePool protocol directly. All it requires is a connect() context manager that yields a psycopg.Connection:

from collections.abc import Iterator
from contextlib import contextmanager

import psycopg


class MyCachePool:
    @contextmanager
    def connect(self) -> Iterator[psycopg.Connection]: ...