Relationship State Resolution

Resolving follow status with a separate query per user card is a textbook N+1 problem. A feed page showing 50 user cards fires 50 individual isFollowing database calls — each a round-trip that adds 5–20ms of latency in a cloud deployment. At 100ms/page the cumulative cost is 5 seconds of blocked rendering. Under ISO 25010:2011 performance-efficiency, this is a structural scalability defect: response time degrades linearly with the number of items displayed, making any growth in user density directly punishing.

Preload follow status alongside the user list in a single query, or use DataLoader to batch all isFollowing checks for a given page render into one database round-trip.

// lib/db.ts — preload approach
export async function getUsersWithFollowStatus(viewerId: string, limit: number) {
  const users = await db.user.findMany({
    take: limit,
    select: {
      id: true,
      name: true,
      avatar: true,
      followers: {
        where: { followerId: viewerId },
        select: { id: true }
      }
    }
  })

  return users.map(u => ({
    ...u,
    isFollowing: u.followers.length > 0,
    followers: undefined
  }))
}

This collapses N+1 queries into a single JOIN, regardless of how many user cards are rendered.