What is the relationship between chunk and extent in MongoDB? Chunk is only logical?
What should I do if I run out of extent reserved space?
Chunk refers to a continuous segment on shard key in a shard. The data in a chunk is continuous on shard key, but it doesn’t necessarily exist in the file. It can be said to be logical.Official documentsThe two links in the explanation in the book explain how it is used in the whole system. (As the saying goes, official documents are getting richer and better organized.)
The extent is a continuous segment in the data file, which is the implementation details. Chunk has nothing to do with it. If you are interested, this slidesUnderstanding MongoDB Storage for Performance and Data SafetyNot bad.