Why do Kafka consumers receive the 'order issued' event before the 'order created' event? How to fix this?

This behavior is usually related to the fact that messages in Kafka can be distributed across different partitions, and consumers read them in parallel, which means the delivery order is not guaranteed between different keys or partitions. If "order created" and "order issued" events are published to different partitions or without a key, the consumer may receive the "order issued" event earlier.

To fix this situation and guarantee the order of events for a single order, you should:

• Use a message key (for example, the order ID) when publishing, so that all events for one order go to the same partition.
• Configure the consumer to read messages from partitions sequentially.

Example in Go when sending messages with a key:

producerMessage := &kafka.Message{
    Key:   []byte(orderID), // key for partitioning
    Value: []byte(eventData),
}
producer.Produce(producerMessage, nil)

Thus, Kafka guarantees the order of messages within a single partition, and the consumer will receive events in the correct order.