Discuss MongoDB C100DBA Exam Topic 1 Question 9

Given a replica set with five data-bearing members, suppose the primary goes down with operations in its oplog that have been copied from the primary to only one secondary. Assuming no other problems occur, which of the following describes what is most likely to happen?

Amissing operations will need to be manually re-performed

Bthe secondary with the most current oplog will be elected primary

Creads will be stale until the primary comes back up

Dthe primary may roll back the operations once it recovers

Ethe most current secondary will roll back the operations following the election

Suggested Answer: B

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13 comments · newest first

Ricarda 11 months ago

E seems off, I doubt the secondary will roll back anything.

Amie 12 months ago

Wait, can the primary really roll back ops? Sounds risky!

Johana 12 months ago

C makes sense too, reads will be stale for sure.

Lenny 12 months ago

I think B is more likely, that secondary could become primary.

Joana 1 year ago

A is definitely true, missing ops need to be redone.

Crissy 1 year ago

I vaguely remember that if the primary recovers, it might roll back operations, but I’m not entirely certain how that interacts with the election process.

Quiana 1 year ago

I practiced a similar question, and I feel like reads might be stale until the primary comes back up, but I can't recall the exact details.

Daren 1 year ago

I remember something about how the oplog works, but I'm not sure if the secondary can just take over without issues.

Tanesha 1 year ago

I think the secondary with the most current oplog will be elected primary, but I'm a bit confused about the rollback implications.

Katie 1 year ago

The ability to use globals with decision tables is an interesting point, but I'm not sure if that's a significant advantage over if-then rules. I'll have to weigh the pros and cons of each approach.

German 1 year ago

Okay, I've got this. The key is to use a lookup to filter the data and find the relevant information to resolve CustomerB's issue. Options A and B are the correct answers here.

Sanda 1 year ago

Okay, I think I've got this. The key is to identify the reason the account is in this particular status, based on the information provided. Let me work through the options.

Zita 1 year ago

I think I learned that `git checkout` is mostly for switching branches or restoring files, so that doesn't apply here. Not really sure about `git clean`, though.

MongoDB C100DBA Exam - Topic 1 Question 9 Discussion