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Questions tagged [cqrs]

Command Query Responsibility Segregation design pattern

299 questions
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2 answers

CQRS and validations

I'm starting to introduce myself in CQRS concepts, but I get stucked with the following situation: Supouse you have an entity that must have an unique name. In order to verify that, prior to create the entity you must make a query, thus you are…
Apocatastasis
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Pushing complete notifications to client

So with cqrs, we accept that consistency is eventual. However, that doesn't mean that the user has to continually poll, or that eventual means an update has to take more then 500ms to sync. For the sake of UX, we want to at least give the illusion…
anon
2
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1 answer

Moving from CRUD to CQRS: how to identify appropriate command-event relationships?

We have an existing CRUD-based system, but are hitting a number of pain points keeping the data organised for all the various views that are increasingly required of it. I'm assessing whether splitting the read and write models (i.e. CQRS) might…
eggyal
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2
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2 answers

Are CQRS and Hexagonal Architecture incompatible?

I am beginning a project and I was wondering If I can use CQRS and Hexagonal architecture in the same project, or in fact they are incompatible. I read about CQRS and some people agree that it is not an architecture, and more like a pattern. What do…
jpadilladev
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2
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1 answer

Separation versus Segregation

The term "segregation" is used in the CQRS pattern. What's the difference between segregation versus separation in this case?
jgauffin
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2 answers

CQRS and events order

I'm learning cqrs right now. Problem My concern is event ordering. Assumption 1: user service is creating user and three events in order. Each event was sent after each step was finished in write model. Event A: user ABC created Event B: changed…
Krzysztof
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0
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1 answer

Contextual Data on CQRS Requests

I use CQRS for most of my applications. My request objects contain the data needed by the Handler to perform the Request. However, I've started to realize that some data points we have are required on every single request and are more contextual to…
mccow002
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0
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3 answers

Is CQRS CQRS without separate read and write data stores?

Is having a separate read only and write only data store a core part of CQRS, or does it still make sense in some scenarios to do CQRS with a single data store? Asking because a coworker is using CQRS terminology in a project. Whether or not he's…
BVernon
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In CQRS, how does the event processor know how to populate the read-side database?

I'm currently playing around with a CQRS implementation and I'm having some trouble understanding the following concept: Event Bus for publishing update events (required): Whenever the write database is updated, a change notification is published…
user7467314
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