如何保留查看表更新CQRS/事件采购模式
使用CQRS/事件采购模式，将视图表保持最新的最佳方法是什么？
最常见的方法是通过KSQL查询，但是我想知道是否有一种更通用的方法，例如使用关系数据库。
您的应用程序运行的时间越多，您将不得不读取更多数据，从而使此数据不可持续。 您如何处理？您是否只阅读所有事件并在执行一个新命令时对它们进行计算？
What is the best way to keep a view table up to date, using the CQRS/Event Sourcing pattern?
The most common way is through KSQL queries, but I would like to know if there is a more generic way, for example, using a relational database.
The more time your app is running, you will have to read more data, making this unsustainable.
How do you deal with this? Do you just read all the events and compute them every time one new command is executed?
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典型的方法是存储在事件流中的视图状态的一部分（即偏移）。例如，您的视图可以存储事件流中某些分区（例如实体ID）的事件1003的当前。在查询该分区中的事件时，更新视图表的过程会在1003之后询问事件。一个人可以定期触发该过程，或者连续运行或作为写作命令过程的一部分发出信号。
一个观点之一可以是“将这些事件发布给卡夫卡”；在这种情况下，其他视图可以使用消费者组/偏移提交功能来处理事件，而不是一开始。
The typical approach to this is to store as part of the view's state where it is in the event stream (i.e. an offset). For example, your view can store that it's current up through event 1003 for some partition (e.g. an entity ID) in the event stream. When querying for events in that partition, the process updating the view table asks for events after 1003. One can trigger that process periodically, or have it run continuously, or signalled as part of the process of writing commands.
One of the views can be "publish these events to Kafka"; in which case other views can use the consumer group/offset commit functionality to process the events at-least-but-typically-not-more-than-once.