Connection pool

Prisma Client uses a connection pool of database connections (managed by the database driver when using driver adapters). The pool is created when Prisma Client opens the first connection to the database, which can happen in one of two ways:

• By explicitly calling $connect() or
• By running the first query, which calls $connect() under the hood

Relational database connectors use Prisma ORM's own connection pool, and the MongoDB connectors uses the MongoDB driver connection pool.

Starting with Prisma ORM v7, relational datasources instantiate Prisma Client with driver adapters by default. Driver adapters rely on the Node.js driver you supply, so connection pooling defaults (and configuration) now come from the driver itself.

Use the tables below to translate Prisma ORM v6 connection URL parameters to the Prisma ORM v7 driver adapter fields alongside their defaults.

The following tables document the default connection pool settings for each driver adapter.

Here are the default connection pool settings for the pg driver adapter:

import { PrismaPg } from "@prisma/adapter-pg";

const adapter = new PrismaPg({

  connectionString: process.env.DATABASE_URL,

  // Match Prisma ORM v6 defaults:

  connectionTimeoutMillis: 5_000, // v6 connect_timeout was 5s

  idleTimeoutMillis: 300_000, // v6 max_idle_connection_lifetime was 300s

});

Here are the default connection pool settings for the mariadb driver adapter:

import { PrismaMariaDb } from "@prisma/adapter-mariadb";

const adapter = new PrismaMariaDb({

  host: "localhost",

  port: 3306,

  user: process.env.DB_USER,

  password: process.env.DB_PASSWORD,

  database: process.env.DB_NAME,

  // Match Prisma ORM v6 defaults:

  connectTimeout: 5_000, // v6 connect_timeout was 5s

  idleTimeout: 300, // v6 max_idle_connection_lifetime was 300s (note: in seconds, not ms)

});

Here are the default connection pool settings for the mssql driver adapter:

import { PrismaMssql } from "@prisma/adapter-mssql";

const adapter = new PrismaMssql({

  server: "localhost",

  port: 1433,

  database: "mydb",

  user: process.env.DB_USER,

  password: process.env.DB_PASSWORD,

  // Match Prisma ORM v6 defaults:

  connectionTimeout: 5_000, // v6 connect_timeout was 5s

  pool: {

    idleTimeoutMillis: 300_000, // v6 max_idle_connection_lifetime was 300s

  },

});

The MongoDB connector does not use the Prisma ORM connection pool. The connection pool is managed internally by the MongoDB driver and configured via connection string parameters.

The pool size cannot exceed what the underlying database can support. Configure pool size and timeouts via your driver adapter (see the tables above). This is a particular challenge in serverless environments, where each function manages an instance of PrismaClient and its own connection pool.

Consider introducing an external connection pooler like PgBouncer to prevent your application or functions from exhausting the database connection limit.

When using Prisma Client with a driver adapter, database connections are managed by the driver and its pool. They are not exposed to the developer and it is not possible to manually access individual connections.