What is Oplog tailing?
Tailing a MongoDB collection, or the entire database by way of tailing the oplog, is a perfect match for such a programming model! It means the application server will be notified real-time of any changes happening in the entire database.
What is an Oplog?
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.
Where can you find the Oplog?
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 replication Oplog?
Replication Oplog Window is (X) occurs if the approximate amount of time available in the primary replication oplog meets or goes below the specified threshold. This refers to the amount of time that the primary can continue logging given the current rate at which oplog data is generated.
What is MongoDB Oplog?
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. MongoDB applies database operations on the primary and then records the operations on the primary’s oplog.
What is Tailable cursor?
A tailable cursor performs a collection scan over a capped collection. It remains open even after reaching the end of the collection. Applications can continue to iterate the tailable cursor as new data is inserted into the collection.
What is the risk of having a small Oplog?
Risks with the oplog are related to its being capped: if your oplog is too small, any maintenance operations that require you to take down a replica can cause the copy to fail.
What is Oplog in nutanix?
Oplog is a subset of SSDs which is used to handle the random IOPs. Sequential OPs are served from the Extend store which is a combination of SSDs and HDDs.
What happens to replica set Oplog if it runs out of memory?
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.
What is cursor in mongoose?
In MongoDB parlance, a cursor is an object that you can use to iterate through the results of a query. js driver will return a cursor from find() . In most cases the cursor API is overkill, so mongoose hides it from you by default.
What is a Tailable cursor in MongoDB?
What is local Oplog RS?
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.