Would the commands replicated in the order executed always?

[WeihanLi]

Hi team, we're using Redis Hash as a secondary storage and Stream for incremental changes sync, and we're using Redis in a master-slave mode, one master/multiple slaves and slaves are all readonly.
We would write updated data into Redis, and then add an entry in the stream. Is there any scene that the commands replicated are not in the order executed?

For example, we would execute HSET X a "aa" then XADD StreamX in master, would it be executed in the order XADD StreamX then HSET X a "aa" in slave in some cases?

If yes, is there any solution for that? Would Redis Transaction help?

[sundb]

@WeihanLi the order the commands are replicated is always the same as the order they are executed, otherwise it will lead to inconsistencies between the master and the slave, just as SET k 1 and DEL k, in the opposite order will have different results.

[WeihanLi]

@sundb thanks very much for the quick reply, according to the chatgpt(maybe wrong, so come for a confirmation from you Redis experts), "when across keys, the replication order may differ", so is it correct? Since we're handling two keys when handling storage and stream updates, would the orders across keys differ when replicated to slave nodes? Thanks

[sundb]

The asynchronous model is not directly related to the order in which the commands are replicated. asynchronous means that the commands that need to be replicated will be put into the replication backlog, and the backlog will be sent to the replications in the cron. However, the order of commands in the backlog is still the same as the order in which they are executed.

[WeihanLi]

Thank very much