SurrealDB Driver

The SurrealDB driver persists events to a SurrealDB database using the official surrealdb JavaScript SDK (v2). It supports SurrealDB server 3.x.

import { createEventStore, createAggregateRoot } from '@requence/event-sourcing/surreal'
import { Surreal } from 'surrealdb'

const db = new Surreal()
await db.connect(process.env.SURREALDB_URL!)
await db.use({ namespace: 'app', database: 'app' })

const eventStore = createEventStore({
  database: db,
  aggregateRoots: [userAggregateRoot],
})

Database Schema

The driver uses SCHEMAFULL tables mirroring the PostgreSQL layout:

Table	Purpose
`events`	Append-only event log with position, stream, and metadata
`event_sourcing_counters`	Counter record providing the gapless global event position
`checkpoints`	Last-processed position (and optimistic-concurrency `version`) per projection/process manager
`aggregate_root_snapshots`	Cached aggregate state for fast rehydration
`projection_snapshots`	Cached projection state for snapshot-based projections
`projection_applied_events`	Counter for snapshot frequency tracking

By default the driver creates the schema itself: idempotent DEFINE ... IF NOT EXISTS statements run lazily before the first operation. Pass initSchema: false to opt out and manage the schema yourself — the DDL is exported for that purpose:

import { initSchema, SCHEMA_STATEMENTS } from '@requence/event-sourcing/surreal'

await initSchema(db) // or run SCHEMA_STATEMENTS through your own tooling

Configuration

const eventStore = createEventStore({
  // Required — connected Surreal instance (namespace/database selected) or factory
  database: db,

  // Required — one or more aggregate roots
  aggregateRoots: [user, project],

  // Optional — disable automatic schema creation (default: true)
  initSchema: false,

  // Optional — distributed lock for multi-instance deployments
  lock: redisLock(redis),

  // Optional — disable automatic initialization
  autoInit: false,

  // Optional — callback invoked after events are appended
  onEventsAppended(events) {
    // e.g. broadcast via WebSocket
  },

  // Optional — replay and refresh progress callbacks
  onProjectionReplay: { /* ... */ },
  onProcessManagerRefresh: { /* ... */ },

  // Optional — post-process events before persistence
  postProcessEvent(event, aggregateRoot) {
    return event
  },
})