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Connection management

PrismaClient connects and disconnects from your data source using the following two methods:

In most cases, you do not need to explicitly call these methods. PrismaClient automatically connects when you run your first query, creates a connection pool, and disconnects when the Node.js process ends.

See the connection management guide for information about managing connections for different deployment paradigms (long-running processes and serverless functions).

$connect()​

It is not necessary to call $connect() thanks to the lazy connect behavior: The PrismaClient instance connects lazily when the first request is made to the API ($connect() is called for you under the hood).

Calling $connect() explicitly​

If you need the first request to respond instantly and cannot wait for a lazy connection to be established, you can explicitly call prisma.$connect() to establish a connection to the data source:

const prisma = new PrismaClient()

// run inside `async` function
await prisma.$connect()

$disconnect()​

When you call $disconnect() , Prisma Client:

  1. Runs the beforeExit hook
  2. Ends the Query Engine child process and closes all connections

In a long-running application such as a GraphQL API, which constantly serves requests, it does not make sense to $disconnect() after each request - it takes time to establish a connection, and doing so as part of each request will slow down your application.

tip

To avoid too many connections in a long-running application, we recommend that you use a single instance of PrismaClient across your application.

Calling $disconnect() explicitly​

One scenario where you should call $disconnect() explicitly is where a script:

  1. Runs infrequently (for example, a scheduled job to send emails each night), which means it does not benefit from a long-running connection to the database and
  2. Exists in the context of a long-running application, such as a background service. If the application never shuts down, Prisma Client never disconnects.

The following script creates a new instance of PrismaClient, performs a task, and then disconnects - which closes the connection pool:

import { PrismaClient } from '@prisma/client'

const prisma = new PrismaClient()
const emailService = new EmailService()

async function main() {
  const allUsers = await prisma.user.findMany()
  const emails = allUsers.map((x) => x.email)

  await emailService.send(emails, 'Hello!')
}

main()
  .then(async () => {
    await prisma.$disconnect()
  })
  .catch(async (e) => {
    console.error(e)
    await prisma.$disconnect()
    process.exit(1)
  })

If the above script runs multiple times in the context of a long-running application without calling $disconnect(), a new connection pool is created with each new instance of PrismaClient.

Exit hooks​

info

From Prisma ORM 5.0.0, the beforeExit hook only applies to the binary Query Engine.

The beforeExit hook runs when Prisma ORM is triggered externally (e.g. via a SIGINT signal) to shut down, and allows you to run code before Prisma Client disconnects - for example, to issue queries as part of a graceful shutdown of a service:

const prisma = new PrismaClient()

prisma.$on('beforeExit', async () => {
  console.log('beforeExit hook')
  // PrismaClient still available
  await prisma.message.create({
    data: {
      message: 'Shutting down server',
    },
  })
})