Database Adapters

Federation no longer accepts a raw Drizzle database. It accepts a Database instance derived from @downcity/city; the adapter owns the driver, transactions, DDL, and connection lifecycle.

SQLite

pnpm add @downcity/city @downcity/database-sqlite

import { Federation } from "@downcity/city";
import { Database } from "@downcity/database-sqlite";

const database = new Database({ filename: "./federation.sqlite" });
const federation = new Federation({ database });

Use filename: ":memory:" in tests. File databases enable WAL by default.

Cloudflare D1

import { Federation } from "@downcity/city";
import { Database } from "@downcity/database-d1";

const database = new Database({ binding: env.DB });
const federation = new Federation({ database });

The D1 adapter provides the same context.transaction() contract through snapshots, conflict retries, and atomic batch() commits. Reads inside a transaction observe its buffered writes.

PostgreSQL

import { Federation } from "@downcity/city";
import { Database } from "@downcity/database-postgresql";

const database = new Database({ url: process.env.DATABASE_URL! });
const federation = new Federation({ database });

The PostgreSQL adapter uses postgres-js and native Drizzle transactions.

Service boundary and lifecycle

Services use context.table() and context.transaction(). Selected official integrations can use the restricted context.database.query() / atomic() surface, but never receive the underlying driver client.

Federation owns the supplied database. Call await federation.dispose() during shutdown to release adapter resources. Disposal is idempotent, and operations after disposal fail.