Instantiating the client

The following example demonstrates how to import and instantiate your generated client from the default path:

import { PrismaClient } from '@prisma/client'

const prisma = new PrismaClient()

The number of PrismaClient instances matters

Your application should generally only create one instance of PrismaClient. How to achieve this depends on whether you are using Prisma in a long-running application or in a serverless environment .

The reason for this is that each instance of PrismaClient manages a connection pool, which means that a large number of clients can exhaust the database connection limit. This applies to all database connectors.

If you use the MongoDB connector, connections are managed by the MongoDB driver connection pool. If you use a relational database connector, connections are managed by Prisma's connection pool. Each instance of PrismaClient creates its own pool.

1. Each client creates its own instance of the query engine.

2. Each query engine creates a connection pool with a default pool size of:

   • num_physical_cpus * 2 + 1 for relational databases
   • 100 for MongoDB

3. Too many connections may start to slow down your database and eventually lead to errors such as:

   Error in connector: Error querying the database: db error: FATAL: sorry, too many clients already
       at PrismaClientFetcher.request