CQRS stands for Command Query Responsibility Segregation. Already a lot has been written about this subject. The main concepts I would like to take out are the followings:
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Separate state changing actions as update, modify and delete from the read! I can not emphasize the importance to make your mind ready of seeing the world as this. I guarantee you: Reads make the most of your systems. Most time a user reads data. If you succeed here to give him fast response you already reached a lot!
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Be prepared to offer different PERFORMANT views of your domain. And keep in mind you can create these views without the normal database modelling approach. It does really not matter in which normalization form you are in. When I use the term 'view' it includes classical database views as well as asynchronous propagated database tables. It really depends on your use case.
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To make the separation explicit I suggest using the following terms:
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-Query: This is the read
-Command: This is the create, update and delete
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