MongoDB Best Practices

Priority: P0 (CRITICAL)

Schema Design

• Embed vs Reference:
• Embed (1:Few): Addresses, Phone Numbers. Optimization: Read locality.
• Reference (1:Many/Infinity): Logs, Activity History. Optimization: Document size limits (16MB).
• Bucket Pattern: For time-series or high-cardinality "One-to-Many", bucket items into documents (e.g., DailyLog).

Optimize Indexes

• ESR Rule: Equality, Sort, Range. Order your index keys (status, date, price) if you query status='A', sort by date, filter price > 10.

See implementation examples for compound index and pagination patterns.

• Text Search: Use $text search instead of $regex for keywords. $regex slow (linear scan) unless anchored (^prefix).
• Covered Queries: Project only indexed fields to avoid fetching document (PROJECTION key).
• Explain Plan: Target nReturned / keysExamined ratio of ~1. If docsExamined >> nReturned, index inefficient.