Which features of relational database management systems were deliberately omitted in MongoDB and help us to obtain horizontal scalability? Check all that apply.

Question

Options

• AMulti-statement transactions
• BJoins
• CAuthentication

Explanation

A (Multi-statement transactions) and B (Joins) are correct. MongoDB deliberately omitted these two RDBMS features because both are extremely difficult to execute efficiently across a distributed, sharded cluster - enforcing ACID transactions across multiple nodes requires expensive coordination protocols (like two-phase commit), and performing joins across shards requires pulling data from multiple machines, both of which create bottlenecks that kill horizontal scale. By avoiding these, MongoDB can partition (shard) data across many cheap commodity servers with minimal cross-node coordination. C (Authentication) is a distractor - MongoDB fully supports authentication, and authentication is a security concern completely unrelated to scalability architecture.

Memory tip: Think "JOIN and TRANSACTION = coordination = bottleneck." Anything that requires multiple nodes to agree or communicate before responding hurts horizontal scale. Security features like authentication are per-connection and don't require distributed coordination, so they're irrelevant to this tradeoff.

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