Mastering MongoDB 4.x - Second Edition

Jumbo chunks

In rare cases, we may end up with jumbo chunks, chunks that are larger than the chunk size and cannot be split by MongoDB. We may also run into the same situation if the number of documents in our chunk exceeds the maximum document limit.

These chunks will have the jumbo flag enabled. Ideally, MongoDB will keep track of whether it can split the chunk, and, as soon as it can, it will get split; however, we may decide that we want to manually trigger the split before MongoDB does.

The way to do this is as follows:

1. Connect via shell to your mongos router and run the following:

> sh.status(true)

2. Identify the chunk that has jumbo in its description using the following code:

databases:…mongo_books.books...chunks:…            shardB  2 shardA ...