TOPIC OVERVIEW

MongoDB/Replication

Keep multiple copies of your MongoDB data so your application can survive a server failure.

15 QuestionsAdvancedHigh Priority ~12 min read

MongoDB replication keeps multiple copies of the same data across different servers. A replica set normally has a primary that accepts writes and secondary members that replicate the primary's data.

If the primary becomes unavailable, MongoDB can elect another eligible member as the new primary. Replication improves availability and can also support certain read-scaling patterns, but it does not mean every read or write is automatically distributed across all servers.

What you'll walk away knowing

How MongoDB replica sets work

How primary and secondary members interact

How elections and automatic failover work

How replication affects read preferences and write concerns

1Discuss replication in MongoDB?ExpertHigh 2What is Replica Set?ExpertHigh 3What are replica set members?ExpertHigh 4Explain how the Raft consensus algorithm works within MongoDB Replication.ExpertHigh 5What is a 'Rollback' in the context of a replica set, and how do you minimize its occurrence?ExpertHigh 6Deep dive into Write Concern. What happens under the hood when you use { w: 'majority', j: true }?ExpertHigh 7How does 'Read Preference' differ from 'Read Concern'?ExpertHigh 8What is 'Replication Lag' and what are the top three reasons it occurs in a Node.js-backed system?ExpertHigh 9Explain the 'Oplog' (Operations Log) architecture. What happens if the Oplog is too small?ExpertHigh 10You are running a 3-node replica set across two data centers (2 nodes in DC-A, 1 node in DC-B). If the network link between the DCs breaks, what happens to your application's ability to write?ExpertHigh 11When would you use a 'Delayed Member' or a 'Hidden Member'?ExpertHigh

All Topics