# Aurabase NoSQL & Document Store Reference (MongoDB Compatible)

> Documentation: https://aurabase.cloud/en/docs/nosql
> Engine: Isolated BSON/JSON document store per project
> Use cases: Telemetry, e-commerce product catalogs with heterogeneous attributes, user sessions, event logging

## Key Features
- **Dynamic Schema**: Flexible JSON/BSON document storage without pre-defined migrations.
- **Query Operators**: `$eq`, `$ne`, `$in`, `$nin`, `$gt`, `$gte`, `$lt`, `$lte`, `$regex`, `$exists`.
- **Aggregation Pipelines**: Multi-stage transformations with `$match`, `$group`, `$sort`, `$project`, `$unwind`, `$limit`.
- **Advanced Indexing & TTL**: Simple, compound, text indexes, and **TTL** indexes (`expireAfterSeconds`) for automatic document expiration (sessions, caches).
- **Integrated Realtime CDC**: NoSQL mutations are captured via Change Streams and distributed over the NATS JetStream bus with the same unified payload envelope as Postgres CDC.

## SDK Usage Examples
```typescript
// 1. Insert
await aura.nosql.collection('logs').insertOne({
  level: 'warn',
  message: 'Failed login attempt',
  ip: '192.168.1.1',
  timestamp: new Date()
})

// 2. Filtered Query
const { data: logs } = await aura.nosql.collection('logs')
  .find({ level: 'warn' })
  .sort({ timestamp: -1 })
  .limit(20)

// 3. TTL Index (automatic purge after 24 hours)
await aura.nosql.collection('sessions').createIndex({
  keys: { createdAt: 1 },
  options: { expireAfterSeconds: 86400 }
})
```