Prisma in Production: Patterns and Pitfalls After a Dozen Projects

Prisma is the best ORM for TypeScript applications. After using it across a dozen projects, here are the patterns that make it genuinely excellent -- and the pitfalls that catch developers the first time.

Setup

npm install prisma @prisma/client
npx prisma init

This creates prisma/schema.prisma and a .env file with DATABASE_URL.

// prisma/schema.prisma
generator client {
  provider = "prisma-client-js"
}

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

The Singleton Client Pattern

In Next.js serverless functions, you can accidentally create thousands of database connections. Use a global singleton:

// src/lib/db.ts
import { PrismaClient } from "@prisma/client"

const globalForPrisma = globalThis as unknown as {
  prisma: PrismaClient | undefined
}

export const db =
  globalForPrisma.prisma ??
  new PrismaClient({
    log: process.env.NODE_ENV === "development" ? ["query", "error", "warn"] : ["error"],
  })

if (process.env.NODE_ENV !== "production") globalForPrisma.prisma = db

Import db from this file everywhere. Never instantiate PrismaClient directly in route handlers.

Schema Patterns Worth Knowing

Soft Deletes

Don't hard-delete records -- soft delete with a timestamp:

model Post {
  id        String    @id @default(cuid())
  title     String
  content   String    @db.Text
  createdAt DateTime  @default(now())
  updatedAt DateTime  @updatedAt
  deletedAt DateTime?  // null = active, timestamp = deleted
}

// Always filter out soft-deleted records
const posts = await db.post.findMany({
  where: { deletedAt: null }
})

// Soft delete
await db.post.update({
  where: { id },
  data: { deletedAt: new Date() }
})

Audit Trails

Track who changed what:

model Post {
  id        String   @id @default(cuid())
  title     String
  createdBy String
  updatedBy String?
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt

  creator User @relation("PostCreator", fields: [createdBy], references: [id])
  updater User? @relation("PostUpdater", fields: [updatedBy], references: [id])
}

Enum Fields

enum SubscriptionStatus {
  FREE
  TRIAL
  PRO
  CANCELED
}

model User {
  id                 String             @id @default(cuid())
  subscriptionStatus SubscriptionStatus @default(FREE)
}

TypeScript gets full enum type safety from this.

Querying Efficiently

Select Only What You Need

// BAD: fetches all columns including large text fields
const users = await db.user.findMany()

// GOOD: select only needed columns
const users = await db.user.findMany({
  select: {
    id: true,
    name: true,
    email: true,
    // Not: content, image, largeTextField
  }
})

This matters when tables have text columns or JSON blobs. Fetching unused data wastes bandwidth and memory.

Include vs Select for Relations

// Include: add related records to the result
const post = await db.post.findUnique({
  where: { id },
  include: {
    author: true,       // Fetches the full author record
    comments: true,     // Fetches all comments
  }
})

// Select with nested: granular control
const post = await db.post.findUnique({
  where: { id },
  select: {
    title: true,
    author: {
      select: { name: true, image: true }  // Only name and image from author
    },
    _count: { select: { comments: true } }  // Just the count, not the records
  }
})

Pagination

// Cursor-based (better for large datasets)
const posts = await db.post.findMany({
  take: 20,
  skip: 1,
  cursor: { id: lastSeenId },
  orderBy: { createdAt: "desc" },
  where: { deletedAt: null },
})

// Offset-based (simpler, fine for small datasets)
const posts = await db.post.findMany({
  take: 20,
  skip: page * 20,
  orderBy: { createdAt: "desc" },
})

Cursor-based is more efficient for deep pagination (page 50+) because the database doesn't have to scan skipped rows.

Transactions

Use transactions for operations that must succeed or fail together:

// $transaction: all succeed or all roll back
const [order, payment] = await db.$transaction([
  db.order.create({ data: { userId, total } }),
  db.payment.create({ data: { userId, amount: total } }),
])

// Interactive transactions: for complex logic
const result = await db.$transaction(async (tx) => {
  const user = await tx.user.findUnique({ where: { id: userId } })

  if (user.tokensUsed >= user.tokensLimit) {
    throw new Error("Token limit exceeded")
  }

  await tx.user.update({
    where: { id: userId },
    data: { tokensUsed: { increment: tokensToAdd } }
  })

  return tx.message.create({ data: { userId, content, tokens: tokensToAdd } })
})

Migrations

# Development: creates migration + applies it
npx prisma migrate dev --name descriptive-name

# Production: applies pending migrations (no new migration created)
npx prisma migrate deploy

# Check migration status
npx prisma migrate status

# Reset database (DESTRUCTIVE -- dev only)
npx prisma migrate reset

Golden rule: Never edit a migration file after it's been applied. If you need to change a schema, create a new migration.

Common Mistakes

Not using the singleton: Creates too many connections in serverless environments. Use the global singleton pattern.

N+1 queries: Fetching related records in a loop instead of using include:

// BAD: N+1 (1 query for posts, N queries for authors)
const posts = await db.post.findMany()
for (const post of posts) {
  post.author = await db.user.findUnique({ where: { id: post.authorId } })
}

// GOOD: 1 query with join
const posts = await db.post.findMany({ include: { author: true } })

Running migrations manually in production: Use prisma migrate deploy in your build pipeline. Manual migration is error-prone and hard to track.

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The Prisma setup (schema, singleton, migration pipeline, Neon/Vercel integration) is pre-configured in the AI SaaS Starter Kit.

AI SaaS Starter Kit ($99) ->

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