---
title: Data Connections
---

# Data Connections

This guide helps you quickly enable conversation history storage with a backend that matches your environment.

<div class="prerequisites" markdown>

#### Before you begin

- Completed the [Getting Started](index.md) guide
- SMG running with at least one worker

</div>

---

## Choose a Backend

SMG supports these history backends via `--history-backend`:

- `memory` (default): in-process, non-persistent
- `none`: disable history storage
- `postgres`: durable relational storage
- `redis`: fast key-value storage with optional retention
- `oracle`: enterprise Oracle backend

---

## Quick Start Commands

### Memory (default)

```bash
smg \
  --worker-urls http://worker:8000 \
  --history-backend memory
```

### No history

```bash
smg \
  --worker-urls http://worker:8000 \
  --history-backend none
```

### PostgreSQL

```bash
smg \
  --worker-urls http://worker:8000 \
  --history-backend postgres \
  --postgres-db-url "postgres://user:password@localhost:5432/smg" \
  --postgres-pool-max-size 16
```

On a new database, also set `DB_AUTO_MIGRATE=true` for the first start; see [Schema migrations](#schema-migrations).

### Redis

```bash
smg \
  --worker-urls http://worker:8000 \
  --history-backend redis \
  --redis-url "redis://localhost:6379" \
  --redis-pool-max-size 16 \
  --redis-retention-days 30
```

Set `--redis-retention-days=-1` for persistent retention. Keep the `=`: the Rust CLI rejects `-1` as a separate argument.

### Oracle

```bash
smg \
  --worker-urls http://worker:8000 \
  --history-backend oracle \
  --oracle-wallet-path /path/to/wallet \
  --oracle-tns-alias mydb_high \
  --oracle-user admin \
  --oracle-password "$ORACLE_PASSWORD"
```

!!! note "Python launcher flag names"
    These commands use the Rust `smg` binary's flag names. The Python launcher (`smg launch` from pip, and the container image) spells four of them differently: `--postgres-pool-max`, `--redis-pool-max`, `--oracle-username`, and `--oracle-connect-descriptor` (for `--oracle-dsn`). See [Python Launcher Differences](../reference/configuration.md#python-launcher-differences).

---

## Schema migrations

PostgreSQL and Oracle track a schema version and refuse to start while migrations are pending, printing the SQL to apply by hand. A new database has pending migrations, so set `DB_AUTO_MIGRATE=true` (or `1`) to let SMG apply them at startup:

```bash
DB_AUTO_MIGRATE=true smg launch \
  --worker-urls http://worker:8000 \
  --history-backend postgres \
  --postgres-db-url "postgres://user:password@localhost:5432/smg"
```

A `--schema-config` file can set `auto_migrate` instead. See [Chat History](../concepts/data/chat-history.md#schema-migrations).

---

## Required Flags by Backend

| Backend | Required flags |
|---------|----------------|
| `memory` | none |
| `none` | none |
| `postgres` | `--postgres-db-url` |
| `redis` | `--redis-url` |
| `oracle` | `--oracle-user`, `--oracle-password`, and one of (`--oracle-dsn`) or (`--oracle-wallet-path` + `--oracle-tns-alias`) (omit user/password when `--oracle-external-auth` is set) |

---

## Environment Variables

You can provide Oracle credentials via environment variables (both the Rust binary and the Python launcher read them):

- `ATP_WALLET_PATH`
- `ATP_TNS_ALIAS`
- `ATP_DSN`
- `ATP_USER`
- `ATP_PASSWORD`
- `ATP_EXTERNAL_AUTH`
- `ATP_POOL_MIN`
- `ATP_POOL_MAX`
- `ATP_POOL_TIMEOUT_SECS`

The Rust `smg` binary reads no environment variables for PostgreSQL or Redis. Only the Python launcher reads `POSTGRES_DB_URL`, `POSTGRES_POOL_MAX`, `REDIS_URL`, `REDIS_POOL_MAX`, and `REDIS_RETENTION_DAYS`, as defaults for its flags.

---

## Verify

```bash
curl http://localhost:30000/health
```

If startup fails, SMG returns a config validation error (for example missing DB URL or Oracle credentials). PostgreSQL and Oracle also connect at startup to create tables and check migrations, so an unreachable database or pending migrations stop startup. Redis connects on first use, so a Redis problem shows up on the first request that stores or reads history.

---

## Next Steps

- [Chat History Concepts](../concepts/data/chat-history.md) — backend architecture and tradeoffs
- [Configuration Reference](../reference/configuration.md#storage-configuration) — full storage flag reference