Too many instances of PrismaClient

Bug description

I’m getting the classic FATAL: remaining connection slots are reserved for non-replication superuser connections error for my Postgres DB because there are too many PrismaClient instances going on.

Problem is, I’m using REST API routes (using NextJS) and not GraphQL, so each time there’s an incoming request to a route (and there are many), I’m instantiating a PrismaClient, which results in the aforementioned error.

Is there a way to avoid this?

Environment & setup

• OS: macOS
• Database: PostgreSQL
• Node.js version: 12.6.0
• Prisma version:

2.11.0

[OliverGilan]

Works like a charm, @vladandrei0.

module

import { PrismaClient } from '@prisma/client'

// See here: https://github.com/prisma/prisma-client-js/issues/228#issuecomment-618433162
let prisma

if (process.env.NODE_ENV === 'production') {
	prisma = new PrismaClient()
}
// `stg` or `dev`
else {
	if (!global.prisma) {
		global.prisma = new PrismaClient()
	}

	prisma = global.prisma
}

export default prisma

API

e.g. /api/payments/create

import prisma from 'lib/utils/prisma'

const ApiPaymentsCreate = async (req, res) => {
  ...
  return await prisma.payment.create({...})
}

export default ApiPaymentsCreate

However, a drawback is that referencing Prisma Client indirectly stops the auto-completion (at least in VS Code). A workaround is to temporarily enable while creating the API:

// import prisma from 'lib/utils/prisma'
import { PrismaClient } from '@prisma/client'
const prisma = new PrismaClient()

and then to disable it once done:

import prisma from 'lib/utils/prisma'

I understand how and why this works during development but why is the issue not present for production? Why is it okay to create a new prisma client each time while running in production?

Edit: I read some more and realize now that in a production setting the above solution gets cached the first time the module is loaded so you don’t run into the issue. Only during development does NextJS clear the cache for hot reloading purposes. Leaving comment in case others have same confusion.

[heymartinadams]

Works like a charm, @vladandrei0.

module

import { PrismaClient } from '@prisma/client'

// See here: https://github.com/prisma/prisma-client-js/issues/228#issuecomment-618433162
let prisma

if (process.env.NODE_ENV === 'production') {
	prisma = new PrismaClient()
}
// `stg` or `dev`
else {
	if (!global.prisma) {
		global.prisma = new PrismaClient()
	}

	prisma = global.prisma
}

export default prisma

API

e.g. /api/payments/create

import prisma from 'lib/utils/prisma'

const ApiPaymentsCreate = async (req, res) => {
  ...
  return await prisma.payment.create({...})
}

export default ApiPaymentsCreate

However, a drawback is that referencing Prisma Client indirectly stops the auto-completion (at least in VS Code). A workaround is to temporarily enable while creating the API:

// import prisma from 'lib/utils/prisma'
import { PrismaClient } from '@prisma/client'
const prisma = new PrismaClient()

and then to disable it once done:

import prisma from 'lib/utils/prisma'