Why Use Indexes? — Interview Answer — MongoDB Technical Interview Questions & Answers

Model answer covering query performance trade-offs.

Why Use Indexes? — Interview Answer

  • Model answer: Indexes avoid collection scans. Default index on _id. createIndex on fields you filter/sort.
  • Trade-off: faster reads, slower writes, extra disk.
  • Prove with explain IXSCAN.

Technical Interview Tip: Index + trade-off + explain.

Code Examples for Why Use Indexes? — Interview Answer

Why Use Indexes? — Interview Answer — working example

db.users.createIndex({ email: 1 }, { unique: true })
db.users.createIndex({ city: 1, age: -1 })
db.users.getIndexes()

Why Use Indexes? — Interview Answer — indexes speed reads; unique indexes also enforce constraints. Compound indexes support multi-field filters/sorts.

How to Explain Why Use Indexes? — Interview Answer to an Interviewer

Why indexes?

Faster queries Cost on writes