Oplog storage method

When configuring Replica Set, I know that that uses oplog to synchronize data.

However, I wonder if secondary pools the primary’s oplog and stores it in a particular space (ex: cache area or journal) before applying oplog.

If there is a separate space, are there options for controlling that space?

Hi @Kim_Hakseon ,

AFAIK, Oplog is first stored in the secondary oplog and then applied by 16 replication threads.

The defaults are mostly good for almost all workloads so unless there is a support indication to tune this I would stick to defaults.

What is highly important to decide is the read and write concerns on the driver side as well as readPreference those will have a main impact on replication behaviour.


Thank you so much.

In the other DB (ex: Redis, etc), there was another space that went through before storing it in a log like oplog, so I was asking how MongoDB was doing.

Once again, thank you for your kind reply.

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