MongoDB Best Practices

Priority: P0 (CRITICAL)

Rules

• Model from access patterns: data read together should usually live together.
• Embed for bounded one-to-few data; reference for unbounded growth or independent lifecycle.
• Build indexes for real queries, not theoretical flexibility. Use ESR ordering for equality -> sort -> range compound indexes.
• Use transactions only when single-document guarantees are insufficient.

Verify

• Embed vs reference choice matches cardinality and lifecycle.
• Compound index order matches equality -> sort -> range access.
• Large pagination uses cursor patterns, not deep skip().
• Explain output supports the chosen indexes; review keysExamined and docsExamined.
• Unbounded arrays and hot shard keys were reviewed.

Anti-Patterns