Multi-Database Sync

Multi-Database Sync

One of Walsync’s key advantages is efficiently syncing multiple SQLite databases from a single process.

Configuration

Create a walsync.toml to define multiple databases:

[storage]
bucket = "my-bucket"
endpoint = "https://fly.storage.tigris.dev"

[[databases]]
path = "/data/users.db"
prefix = "users"

[[databases]]
path = "/data/orders.db"
prefix = "orders"

[[databases]]
path = "/data/analytics.db"
prefix = "analytics"

Then start watching all databases:

walsync watch --config walsync.toml

How It Works

Shared Resources

Walsync maintains a single:

• S3 client with connection pooling for all uploads
• File watcher that monitors all database WAL files
• Configuration context loaded once at startup

Per-Database Isolation

Each database still gets:

• Its own S3 prefix (namespace)
• Independent WAL tracking
• Separate checksum verification
• Individual restore capability

Memory Efficiency

┌─────────────────────────────────────┐
│         Walsync Process             │
├─────────────────────────────────────┤
│  Shared S3 Client     (~20MB)       │
│  File Watcher         (~5MB)        │
│  ─────────────────────────────      │
│  Database 1 state     (~500KB)      │
│  Database 2 state     (~500KB)      │
│  Database 3 state     (~500KB)      │
│  ...                                │
└─────────────────────────────────────┘

Adding more databases adds minimal overhead (~500KB-1MB each).

Use Cases

Multi-Tenant Applications

Each tenant gets their own SQLite database:

[[databases]]
path = "/data/tenants/acme.db"
prefix = "tenants/acme"

[[databases]]
path = "/data/tenants/globex.db"
prefix = "tenants/globex"

Microservices

Each service manages its own database:

[[databases]]
path = "/data/auth.db"
prefix = "services/auth"

[[databases]]
path = "/data/billing.db"
prefix = "services/billing"

Edge Deployments

Containers or edge nodes with multiple databases:

[[databases]]
path = "/app/cache.db"
prefix = "edge/node-1/cache"

[[databases]]
path = "/app/sessions.db"
prefix = "edge/node-1/sessions"

Restoring Individual Databases

Restore any single database without affecting others:

walsync restore --prefix orders -o /data/orders-restored.db

Or restore all databases:

walsync restore-all --config walsync.toml --output-dir /data/restored/