How can I batch-send events to different topics and partitions?

[l-7-l]

For example, a user may purchase items from multiple shops, and at checkout, these orders are merged into a single transaction for one-time payment. This transaction corresponds to multiple orders, each scoped by shop. After a successful payment, multiple order paid events are sent. Order events (such as paid, delivered, refunded, etc.) with the same order_id are sent to the same partition. Currently, batch sending only supports the same partition, which may make it impossible to guarantee the order of events.

[spetz]

Currently, you can make use of Partitioning::messages_key(), whether when using low level client or send_with_partitioning() in IggyProducer. The server will ensure that the messages having the same key, will be always appended to the same partition ID, as long as the number of partitions doesn't change.

[l-7-l]

How to send messages in bulk with the same topic but different partitions?

[spetz]

Currently it's not possible - the batch is treated as a single unit, and all the messages go to the same partition, whether you provide its ID directly, or use either of balanced or message key variants.