> ## Documentation Index
> Fetch the complete documentation index at: https://docs.oauth.fyi/llms.txt
> Use this file to discover all available pages before exploring further.

# Database

> SQLite vs PostgreSQL, and how migrations work.

Which database a bot uses isn't a choice you make — it's built into that bot. Check its
`.env.example` (a `DATABASE_URL` starting with `postgres://` means Postgres; a `DB_PATH` or
similar pointing at a `.db` file means SQLite) if you're not sure which you have.

## SQLite bots

Nothing to set up. The bot creates its database file on first run, at the path set in `.env`
(or a sensible default if unset). Back it up by copying that one file — stop the bot first so
you're not copying mid-write.

## PostgreSQL bots

You need a running Postgres server (13+) before the bot will start.

<Steps>
  <Step title="Start Postgres">
    Easiest via the `docker-compose.yml` most of these bots ship with:

    ```bash theme={null}
    docker compose up -d postgres
    ```

    Or point `DATABASE_URL` at any Postgres server you already run.
  </Step>

  <Step title="Set DATABASE_URL">
    In `.env`: `DATABASE_URL=postgresql://user:password@host:5432/dbname`
  </Step>

  <Step title="Run migrations">
    The Python bots that use Postgres manage schema with Alembic:

    ```bash theme={null}
    alembic upgrade head
    ```

    Do this once before the first start, and again after every update that changes the schema —
    check that update's release notes.
  </Step>
</Steps>

<Warning>
  Never run migrations against a production database without a recent backup. `alembic upgrade
      head` applies every pending migration in order — if one has a bug, you want a way back.
</Warning>

<Card title="Next: hosting" icon="server" href="/sources/hosting">
  Keep it running past your terminal session.
</Card>