Prisma Query Optimizer

Prisma Query Optimizer

Before generating any output, read config/defaults.md and adapt all patterns, imports, and code examples to the user's configured stack.

Analysis Process

1. Locate all Prisma query calls in the specified files or project
2. For each query, check for the issues listed below
3. Output a structured report with findings and fixes

Issues to Detect

N+1 Queries

Look for loops that execute Prisma queries inside:

// BAD: N+1 query
const users = await prisma.user.findMany();
for (const user of users) {
  const posts = await prisma.post.findMany({ where: { authorId: user.id } });
}

// FIX: Use include
const users = await prisma.user.findMany({
  include: { posts: true }
});

Missing Eager Loading

Detect when related data is accessed after the initial query without being included:

// BAD: Lazy loading triggers additional queries
const user = await prisma.user.findUnique({ where: { id } });
console.log(user.posts); // undefined or triggers additional query

// FIX: Include related data upfront
const user = await prisma.user.findUnique({
  where: { id },
  include: { posts: true }
});

Missing Index Hints

Flag queries filtering on fields that likely need indexes:

• Foreign keys used in where clauses
• Fields used in orderBy
• Fields used in unique lookups without @unique

Suggest adding indexes in schema.prisma:

model Post {
  authorId Int
  author   User @relation(fields: [authorId], references: [id])

  @@index([authorId]) // Add this
}

Redundant Queries

Identify duplicate queries that fetch the same data multiple times in a request:

// BAD: Same query twice
const user1 = await prisma.user.findUnique({ where: { id } });
// ... later in same function
const user2 = await prisma.user.findUnique({ where: { id } });

// FIX: Reuse the result
const user = await prisma.user.findUnique({ where: { id } });
// Use 'user' throughout

Unnecessary Select/Include Combinations

Detect overly broad data fetching:

// BAD: Fetching everything when only name is needed
const users = await prisma.user.findMany({
  include: { posts: true, comments: true, profile: true }
});
const names = users.map(u => u.name);

// FIX: Select only what's needed
const users = await prisma.user.findMany({
  select: { name: true }
});

Missing Pagination

Flag findMany without take/skip on large tables:

// BAD: Unbounded query
const allPosts = await prisma.post.findMany();

// FIX: Add pagination
const posts = await prisma.post.findMany({
  take: 20,
  skip: page * 20,
  orderBy: { createdAt: 'desc' }
});

Inefficient Counting

Detect full fetches when only count is needed:

// BAD: Fetching all records to count
const posts = await prisma.post.findMany({ where: { published: true } });
const count = posts.length;

// FIX: Use count
const count = await prisma.post.count({ where: { published: true } });

Output Format

Present findings in this structure:

## Prisma Query Analysis

### Critical Issues
- **N+1 Query** in `src/services/user.ts:45`
  - Issue: Loop executes individual post queries for each user
  - Fix: [code block with corrected query]

### Warnings
- **Missing Index** in `schema.prisma`
  - Issue: `Post.authorId` used in queries but not indexed
  - Fix: Add `@@index([authorId])` to Post model

### Suggestions
- **Over-fetching** in `src/api/users.ts:23`
  - Issue: Including all relations when only user name is used
  - Fix: [code block with select]

### Summary
- Critical: X issues
- Warnings: X issues
- Suggestions: X issues

Reference

See references/patterns.md for additional optimization patterns and advanced techniques.