Appendix A. Concepts for Reference

This appendix contains some additional information that will help you understand the recipes better. We will discuss write concern and read preference in as much detail as possible.

Write concern and its significance

Write concern is the minimum guarantee that the MongoDB server provides with respect to the write operation done by the client. There are various levels of write concern that are set by the client application, to get a guarantee from the server that a certain stage will be reached in the write process on the server side.

The stronger the requirement for a guarantee, the greater the time taken (potentially) to get a response from the server. With write concern, we don't always need to get an acknowledgement ...

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