Database Adapters.

Nextly uses a database adapter pattern that abstracts the database layer behind a common interface. All three adapters extend a shared DrizzleAdapter base class from @nextlyhq/adapter-drizzle, which provides CRUD operations, query building, and transaction management through Drizzle ORM.

Each adapter handles database-specific details: PostgreSQL uses the pg driver with connection pooling and supports JSONB, arrays, and full-text search. MySQL uses mysql2 with connection pooling and workarounds for the missing RETURNING clause. SQLite uses better-sqlite3 with synchronous operations wrapped for async compatibility, WAL mode, and RETURNING clause support (SQLite 3.35+).

You configure your database adapter in nextly.config.ts and Nextly handles the rest: schema creation, migrations, and runtime query execution all go through the adapter.

Key capabilities

• Three Databases — PostgreSQL for production with JSONB, arrays, and full-text search. MySQL for full feature sets. SQLite for development and testing.
• Drizzle ORM — All adapters extend a shared DrizzleAdapter base class. Type-safe queries, schema management, and relational access via the Drizzle instance.
• Connection Pooling — PostgreSQL and MySQL adapters include connection pooling with configurable min/max connections, idle timeouts, and connection timeouts.
• Transaction Support — Full ACID transactions with configurable isolation levels. Automatic retry for serialization failures and deadlocks.

Capabilities by database

• JSONB — PostgreSQL: yes; MySQL: JSON only; SQLite: JSON only
• Array types — PostgreSQL: yes; MySQL: no; SQLite: no
• Full-text search — PostgreSQL: yes; MySQL: FULLTEXT; SQLite: FTS5
• RETURNING clause — PostgreSQL: yes; MySQL: no; SQLite: yes (3.35+)
• Connection pooling — PostgreSQL: pg.Pool; MySQL: mysql2; SQLite: N/A (single file)
• Savepoints — PostgreSQL: yes; MySQL: disabled; SQLite: yes
• ON CONFLICT / upsert — PostgreSQL: yes; MySQL: DUPLICATE KEY; SQLite: yes
• Auto retry — PostgreSQL: serialization + deadlock; MySQL: deadlock; SQLite: no
• Best for — PostgreSQL: production; MySQL: production; SQLite: development / testing

One package per database

• PostgreSQL (@nextlyhq/adapter-postgres, driver: pg / node-postgres) — Full features: JSONB, arrays, full-text search, RETURNING, savepoints, connection pooling.
• MySQL (@nextlyhq/adapter-mysql, driver: mysql2) — Full feature set with workarounds for missing RETURNING clause. Connection pooling and deadlock retry.
• SQLite (@nextlyhq/adapter-sqlite, driver: better-sqlite3) — File-based or in-memory. WAL mode for concurrency. RETURNING clause support (3.35+). Great for development.

Database adapter configuration

PostgreSQL

import { defineConfig } from "nextly/config";
import { createPostgresAdapter } from "@nextlyhq/adapter-postgres";

export default defineConfig({
  database: {
    adapter: createPostgresAdapter({
      url: process.env.DATABASE_URL!,
      pool: {
        min: 0,
        max: 5,
        idleTimeoutMs: 30000,
      },
    }),
  },
});

MySQL

import { defineConfig } from "nextly/config";
import { createMySqlAdapter } from "@nextlyhq/adapter-mysql";

export default defineConfig({
  database: {
    adapter: createMySqlAdapter({
      url: process.env.DATABASE_URL!,
      pool: {
        max: 10,
        idleTimeoutMs: 30000,
      },
    }),
  },
});

SQLite

import { defineConfig } from "nextly/config";
import { createSqliteAdapter } from "@nextlyhq/adapter-sqlite";

export default defineConfig({
  database: {
    adapter: createSqliteAdapter({
      url: "file:./data/app.db",
      wal: true,
      foreignKeys: true,
    }),
  },
});