444 Step Transactions 0d42104a

Use Transactions for Database Operations

Use datasource transactions for database operations within workflows. Transactions commit exactly once and are checkpointed for recovery.

Incorrect (raw database query in workflow):

import { Pool } from "pg";
const pool = new Pool();

async function myWorkflowFn() {
  // Direct database access in workflow - not checkpointed!
  const result = await pool.query("INSERT INTO orders ...");
}

Correct (using a datasource transaction):

Install a datasource package (e.g., Knex):

npm i @dbos-inc/knex-datasource

Configure the datasource:

import { KnexDataSource } from "@dbos-inc/knex-datasource";

const config = { client: "pg", connection: process.env.DBOS_DATABASE_URL };
const dataSource = new KnexDataSource("app-db", config);

Run transactions inline with runTransaction:

async function insertOrderFn(userId: string, amount: number) {
  const rows = await dataSource
    .client("orders")
    .insert({ user_id: userId, amount })
    .returning("id");
  return rows[0].id;
}

async function myWorkflowFn(userId: string, amount: number) {
  const orderId = await dataSource.runTransaction(
    () => insertOrderFn(userId, amount),
    { name: "insertOrder" }
  );
  return orderId;
}
const myWorkflow = DBOS.registerWorkflow(myWorkflowFn);

You can also pre-register a transaction function with dataSource.registerTransaction:

const insertOrder = dataSource.registerTransaction(insertOrderFn);

Available datasource packages: @dbos-inc/knex-datasource, @dbos-inc/kysely-datasource, @dbos-inc/drizzle-datasource, @dbos-inc/typeorm-datasource, @dbos-inc/prisma-datasource, @dbos-inc/nodepg-datasource, @dbos-inc/postgres-datasource.

Datasources require installing the DBOS schema (transaction_completion table) via initializeDBOSSchema.

Reference: Transactions & Datasources