MongoDB Interview Questions. When to choose MongoDB over PostgreSQL? MongoDB: flexible/evolving schema, document-oriented data (nested objects), rapid prototyping, horizontal sharding needs. PostgreSQL: complex queries, …
ReadMongoDB Interview Questions. Q: When would you choose MongoDB over PostgreSQL?. Choose MongoDB when: documents naturally belong together and don't need to be joined (e.g., a blog post with comments, a product with varian…
ReadCRUD & Queries. Core Concepts. Document — JSON-like record (BSON internally). Collection — group of documents (like a table, but schema-less). _id — auto-created ObjectId, globally unique, immutable. Database — namespace…
ReadAggregation & Indexes. Aggregation Pipeline. Stages are processed in order, each stage's output is the next stage's input.. const pipeline = [ // $match — filter (like WHERE, use early to limit docs) { $match: { active: …
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