Replication Commands

Hi all,

I have a quick question about one of the answers for the quiz Replication Commands (

Why is this one of the correct answers when, according to the previous lecture, the time of the earliest entry in the oplog is subject to change (ie., because the oplog is a capped collection)?

The time of the earliest entry in the oplog

This has me scratching me head a bit and I’m a bit confused… How can we obtain information (in a consistent manner) of the earliest entry in the oplog if it in fact, is subject to change?


Hi @juliettet,

Yes, the time of the earliest entry in the oplog is subject to change whenever it is required to flush the data and push in new entries.

Also, since the oplog now contains a new set of entries, the time of the earliest reflected by rs.printReplicationInfo() will be of the new set of entries only.

The question is regarding the information that is obtained using rs.printReplicationInfo() method and not the value of those parameters. Which means, that it will always have a field to illustrate the time of the earliest entry in the oplog, hence it is one of the correct answers.

Curriculum Support Engineer


Thank you for clarifying this for me Muskan!

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Any reason why a couple of threads, like this one, are unlocked?

@Muskan_Sharma has been very busy today :wink:

That makes us busy too as we have to go see if there is something new. 8-(

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Indeed! My guess is @Muskan_Sharma edits posts in order to tag them to their relevant chapter, hence the two toned square.

Hi @steevej-1495 and @007_jb,

We have decided not to close those threads which are conceptual in nature or those threads which has an ongoing discussion regarding any error, issue or concept.

Going forward, we will notify some of our users like you (@steevej-1495 ), @007_jb, @natac13 and @Ramachandra_37567 for any such changes so that you guys don’t end up looking through these threads. :slight_smile:

Yes, the goal is to have the information organised in such a way that our learners can find the relevant information quickly and effortlessly :slight_smile:

We appreciate your engagement with the community. Keep up the good work :slight_smile: :clap:

Shubham Ranjan
Curriculum Support Engineer