Top 3 Nosql Interview Questions
Browse 3 real-world technical and behavioral interview questions about Nosql. Review scenarios, edge cases, and architectural best practices.
You are building a user-profile service. Key-value store or document database: what decides it?
It is decided by everything besides fetching a profile by user id. If every read is by id and every write replaces the whole profile, a key-value store is enough. Login by email, unique emails and field-level updates push towards a document database, or towards index items you maintain yourself.
How do you choose between a document store, a key-value store, a wide-column store and a graph database for a new service?
Compare key-value, document, wide-column and graph databases by access pattern: known-key lookups, aggregate documents, partition-local range reads or unbounded relationship traversal. The right NoSQL choice follows the query shape, not a generic scalability claim. It also connects cassandra to the point an interviewer is testing.
Your service writes a record, reads it straight back, and sometimes gets the old value. What is happening and what do you change?
An acknowledged write is only guaranteed on the replicas that acknowledged it, so a read served elsewhere can legitimately return the previous version. Locate the staleness - replica, secondary index or cache - then buy read-your-writes for that operation only, and price what it costs during a partition.