how to update the state of many aggregates in event sourcing at once

I have one service that I plan to write using the concept of event sourcing and CQRS. The bottom line is that it has an aggregate, let's say a Person. Person{ ID Name // name of person Surname // surname of person ... // other properties County // the country where the person lives } the example is a bit far-fetched, but imagine that the country where a person lives has changed its name. In this case, I need to change the Country property of all aggregates at once. The simplest thing is, I can go to the read model of the service and read the IDs of all the people who live in this country and then create many events for each such person, through which each aggregate will change this property. But it seems to me that this contradicts CQRS, so, in fact, I go from the write model to the read model. So my question is, what is the best way to do this?

Mar 28, 2025 - 04:19

I have one service that I plan to write using the concept of event sourcing and CQRS.

The bottom line is that it has an aggregate, let's say a Person.

Person{
 ID
 Name // name of person
 Surname // surname of person
 
 ... // other properties 

 County // the country where the person lives
}

the example is a bit far-fetched, but imagine that the country where a person lives has changed its name. In this case, I need to change the Country property of all aggregates at once.

The simplest thing is, I can go to the read model of the service and read the IDs of all the people who live in this country and then create many events for each such person, through which each aggregate will change this property. But it seems to me that this contradicts CQRS, so, in fact, I go from the write model to the read model. So my question is, what is the best way to do this?