Why should you care?

Understanding elections helps you set priorities, arbiters, and member counts so the set recovers predictably.

See it live — copy this example

Open mongosh or MongoDB Compass, select database nosqlverse, then run the example. Change one field and run again.

rs.conf()
rs.status().members.forEach(m => {
  print(m.name, m.stateStr, "prio=" + (rs.conf().members.find(c => c.host === m.name) || {}).priority)
})
// Raise priority example (careful in prod):
// cfg = rs.conf(); cfg.members[0].priority = 2; rs.reconfig(cfg)

Run Example »

Edit the code below and click Run to see the result in Toolliyo’s live editor.

What happened?

• rs.conf shows configured priorities.
• rs.status shows current states.
• Higher priority members are preferred as primary if they are caught up.
• Reconfig changes election behavior — use carefully.

Practice next

1. Print rs.conf() and note votes and priority.
2. Identify who can vote.
3. In a lab, set a preferred primary with higher priority.
4. Read about term and electionId in rs.status().
5. Add an arbiter only if you truly need odd votes without more data copies.

Remember

Elections pick the primary. Majority vote is required. Priority influences who wins.

Preferred primary in the main DC

Ops sets higher priority on the in-region member closest to app servers.

Outcome: After maintenance, write traffic returns to the preferred DC.