Database N+1 Query Problem Killing Performance

1. In loop: fetching related data one item at a time instead of using JOIN or batch query
2. Not using Prisma select/include, loading all fields unnecessarily
3. ORM not eager-loading related entities by default
4. Mapping/transforming data in application layer instead of database
5. No query analysis or monitoring to detect N+1 patterns

Use database joins: In SQL, use JOIN to fetch related data in single query. In Prisma, use include(): await prisma.user.findMany({ include: { posts: true } })

Batch queries: If joins not possible, fetch related data in batch: const postsMap = await prisma.post.findMany({ where: { userId: { in: userIds } } })

Enable query logging: Add logging to see duplicate queries. Prisma: set log level, check for repeated queries.

Use select: Don't fetch unnecessary fields: select: { id: true, name: true } instead of full object.