Event Databases

Event databases are persistent storage backends designed to work with the AsyncEventStore. They implement the IAsyncEventDatabase interface and are designed for backends and servers that need to store large amounts of events.

Overview

Event databases serve as the primary persistence layer for the AsyncEventStore. Unlike event caches, which are designed for selective caching of frequently accessed events, event databases are designed to persist all events added to the store. This makes them ideal for:

• Backend services that need to maintain a complete event history
• Relay implementations that store events for other clients
• Server applications that process and store large volumes of events
• Applications that need to work with async database operations

Key Characteristics

Async Interface

Event databases implement the IAsyncEventDatabase interface, which means all operations are asynchronous:

import { AsyncEventStore } from "applesauce-core";
import { LibsqlEventDatabase } from "applesauce-sqlite/libsql";

const database = new LibsqlEventDatabase("file:./events.db");
await database.initialize();

const eventStore = new AsyncEventStore({ database });

// All operations are async
await eventStore.add(event);
const event = await eventStore.getEvent(eventId);
const events = await eventStore.getByFilters({ kinds: [1] });

Complete Persistence

Event databases persist all events added to the store, not just selected ones. When you add an event to an AsyncEventStore with a database backend, it's automatically persisted:

// All events are automatically persisted
await eventStore.add(profileEvent); // Persisted
await eventStore.add(noteEvent); // Persisted
await eventStore.add(reactionEvent); // Persisted

Designed for Scale

Event databases are optimized for storing and querying large numbers of events:

• Efficient indexing for fast queries
• Batch operations for better performance
• Full-text search support (in some implementations)
• Connection pooling and async operations for scalability

Available Implementations

Applesauce provides several event database implementations:

SQLite-Based Databases

Event databases come in two flavors:

Async Databases (require AsyncEventStore):

• LibSQL - Async SQLite with remote support
• Turso - Turso cloud database
• Turso WASM - Turso in the browser

Sync Databases (work with EventStore):

• Better SQLite3 - Synchronous SQLite for Node.js
• Native SQLite - Native SQLite bindings
• Bun SQLite - Bun's built-in SQLite

Note: While sync databases can work with the regular EventStore, this documentation focuses on async databases designed for AsyncEventStore. For sync database usage, see the individual implementation pages.

Choosing an Implementation

Implementation	Environment	Interface	Remote Support	Best For
Better SQLite3	Node.js	Sync	❌	Maximum performance, local storage
Native SQLite	Node.js	Sync	❌	Native bindings, local storage
Bun SQLite	Bun	Sync	❌	Bun applications
LibSQL	Node.js/Browser	Async	✅	Remote databases, Turso
Turso	Node.js	Async	✅	Cloud-hosted databases
Turso WASM	Browser	Async	✅	Browser-based applications

Basic Usage

Creating an Event Database

import { AsyncEventStore } from "applesauce-core";
import { LibsqlEventDatabase } from "applesauce-sqlite/libsql";

// Create the database
const database = new LibsqlEventDatabase("file:./events.db");

// Initialize (required for some implementations)
await database.initialize();

// Create the event store with the database
const eventStore = new AsyncEventStore({ database });

Adding Events

Events are automatically persisted when added to the store:

// Events are automatically persisted to the database
await eventStore.add(event);

Querying Events

All query operations are async:

// Get a single event
const event = await eventStore.getEvent(eventId);

// Check if an event exists
const exists = await eventStore.hasEvent(eventId);

// Query by filters
const events = await eventStore.getByFilters({
  kinds: [1],
  authors: ["pubkey..."],
});

// Get a timeline
const timeline = await eventStore.getTimeline({
  kinds: [1],
  limit: 100,
});

Integration with AsyncEventStore

The AsyncEventStore automatically uses the database for all persistence operations:

import { AsyncEventStore } from "applesauce-core";
import { LibsqlEventDatabase } from "applesauce-sqlite/libsql";
import { RelayPool } from "applesauce-relay";

// Setup
const database = new LibsqlEventDatabase("file:./events.db");
await database.initialize();
const eventStore = new AsyncEventStore({ database });
const pool = new RelayPool();

// Subscribe to relay and persist all events
const subscription = pool.subscription([{ kinds: [0, 1, 3] }]);
subscription.events$.subscribe(async (event) => {
  // Automatically persisted to database
  await eventStore.add(event, event.relay);
});

// Query persisted events
const profiles = await eventStore.getByFilters({ kinds: [0] });
console.log(`Stored ${profiles.length} profiles`);

Advanced Features

Full-Text Search

Some implementations support full-text search:

const database = new LibsqlEventDatabase("file:./events.db", {
  search: true,
});
await database.initialize();

const eventStore = new AsyncEventStore({ database });

// Search events
const results = await eventStore.getByFilters({
  search: "bitcoin lightning",
  kinds: [1],
});

Custom Search Formatters

Customize how content is indexed:

const database = new LibsqlEventDatabase("file:./events.db", {
  search: true,
  searchContentFormatter: (event) => {
    // Extract searchable content
    return event.content + " " + event.tags.map((t) => t[1]).join(" ");
  },
});

Rebuilding Search Indexes

Rebuild search indexes when needed:

await database.rebuildSearchIndex();