What is Oplog in MongoDB?

The oplog (operations log) is a special capped collection that keeps a rolling record of all operations that modify the data stored in your databases.

How do I view an Oplog in MongoDB?

Access the Oplog

  1. Connect to your cluster with the mongosh , using the credentials of the new database user with access to the local database.
  2. Switch to the local database. > use local.
  3. The oplog collection is named oplog.rs .

What happens to a replica set Oplog if it runs out of memory MongoDB?

Question: MongoDB Assessment What happens to a Replica set oplog if it runs out of memory? The oplog will be saved on one of the secondary servers.

Where is the Oplog located?

Oplog is stored in local DB as oplog.rs collection. This is a capped collection but can be tailed using a cursor. In Python, pymongo package can be used to connect to MongoDB and tail the oplog.

What is local Oplog Rs MongoDB?

local.oplog.rs is the capped collection that holds the oplog. You set its size at creation using the oplogSizeMB setting. To resize the oplog after replica set initiation, use the Change the Size of the Oplog procedure. For additional information, see the Oplog Size section.

How do I restore my Oplog?

Recover a database

  1. Dump the MongoDB Oplog to a folder (e.g. ~/oplog): mongodump -u root –authenticationDatabase admin -d local -c oplog.rs -o ~/oplog.
  2. Create a copy of the dump file to ensure you can manipulate it safely: mkdir ~/oplog2 && cp ~/oplog/local/oplog.rs.bson ~/oplog2/oplog.bson.

How do I dump Oplog?

Follow the following steps to do so:

  1. Dump the MongoDB Oplog to a folder (e.g. ~/oplog): mongodump -u root –authenticationDatabase admin -d local -c oplog.rs -o ~/oplog.
  2. Create a copy of the dump file to ensure you can manipulate it safely: mkdir ~/oplog2 && cp ~/oplog/local/oplog.rs.bson ~/oplog2/oplog.bson.