Postgres

@node-ts/bus-postgres stores workflow state in PostgreSQL. This page covers installing and configuring it.

@node-ts/bus-postgresSource

Installation

npm

npm i @node-ts/bus-postgres

pnpm

pnpm add @node-ts/bus-postgres

yarn

yarn add @node-ts/bus-postgres

Create a PostgresPersistence and pass it to the bus configuration:

import { Bus } from '@node-ts/bus-core'
import {
  PostgresConfiguration,
  PostgresPersistence
} from '@node-ts/bus-postgres'
import { messageTypes } from './message-types.generated'
import { fulfilmentWorkflow } from './workflows/fulfilment-workflow'

const postgresConfiguration: PostgresConfiguration = {
  // Passed to a pg Pool
  connection: {
    connectionString: 'postgres://postgres:password@localhost:5432/postgres',
    max: 10
  },
  // Created if it doesn't exist
  schemaName: 'workflows'
}
const postgresPersistence = new PostgresPersistence(postgresConfiguration)

const bus = Bus.configure()
  .withMessageTypes(messageTypes)
  .withPersistence(postgresPersistence)
  .withWorkflow(fulfilmentWorkflow)
  .build()

// Creates a table, and indexes for its lookups, for each workflow state
await bus.initialize()
await bus.start()

Configuration

Option	Description
connection	The pg Pool settings, such as connectionString and max.
schemaName	The schema to create workflow tables in, such as workflows. It's created if it doesn't exist. The name is quoted, so it's case-sensitive and used exactly as given. public works too.

To share a pool with the rest of your application, pass your Pool as the second constructor argument.

Tables

Each workflow state has a table in the schema, named after its $name with invalid characters removed. It has the state's id, its version for optimistic concurrency, and the state itself as jsonb. initialize() creates the tables, and an index for each field that messages are looked up by. It's safe to run from several instances at once.

Running Postgres locally

docker run -d -e POSTGRES_PASSWORD=password -p 5432:5432 postgres

See also

• Workflows
• PostgresConfiguration in the API reference