- **Shared Collection (Discriminator/Tenant ID)**: Best for scale and operational simplicity. Filter all queries by `tenantId` (add `tenantId` as leading key in compound indexes).
- **Separate Databases per Tenant**: Best for strict compliance, data isolation, and easy backup/restore per customer.
- **Separate Collections**: Anti-pattern if tenant counts reach thousands (exceeds namespace limits).

Q59 [Scenario]: Design a multi-tenant SaaS architecture in MongoDB. Should you use single collections, separate databases, or separate collections?

Q60 [Scenario]: Fetching 500,000 documents via Model.find() causes Node.js Out-Of-Memory (OOM) crashes. How do you resolve this?

Q58 [Scenario]: Audit logs must be retained for exactly 90 days and deleted automatically. How do you implement this efficiently?

A progressive question bank covering Core Fundamentals, Schema Design, Queries, Indexes, Aggregation Pipelines, Middleware, Replica Sets, Sharding, and Production Scenarios

Top 70 MongoDB + Mongoose Interview Questions & Scenario Challenges

Q59 [Scenario]: Design a multi-tenant SaaS architecture in MongoDB. Should you use single collections, separate databases, or separate collections? - Top 70 MongoDB + Mongoose Interview Questions & Scenario Challenges

Q59 [Scenario]: Design a multi-tenant SaaS architecture in MongoDB. Should you use single collections, separate databases, or separate collections?

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