{
  "instruction": "Related data loaded without N+1 queries",
  "relevant_when": "Agent builds API endpoints that return records with related data from multiple tables",
  "context": "When loading a list of records with related data (e.g. orders with line items, posts with comments), always use JOINs, batch loading (IN clause), or ORM eager loading (include/prefetch_related). Never query related records inside a loop.",
  "sources": [
    {
      "type": "file",
      "filename": "skills/web-performance/SKILL.md",
      "tile": "tessl-labs/web-performance"
    }
  ],
  "checklist": [
    {
      "name": "no-queries-in-loops",
      "rule": "Database queries are NOT executed inside for/forEach/map loops over a list of parent records. Related data is fetched using JOINs, IN clauses with collected IDs, or ORM eager loading (Prisma include, Sequelize include, Django prefetch_related/select_related). Querying in a loop is a failure even for small datasets.",
      "relevant_when": "Agent loads parent records with related child records"
    },
    {
      "name": "foreign-key-indexes",
      "rule": "When creating database tables, foreign key columns used in JOINs and WHERE clauses have indexes defined",
      "relevant_when": "Agent creates database schema with foreign key relationships"
    }
  ]
}