Multi-Topic subscription across tenant and namespace in Java client

[prakashsaraf7]

The document suggest that we can create a multi-topic subscription across different namespaces. However, in MultiTopicConsumerImpl.java - there are explicit check to make sure all topics belong to one namespace only.
Can you please clarify, if it is possible to create multi-topic subscription across tenant and namespace? Or is it documentation bug?

[skyrocknroll]

@prakashsaraf7 You can create multiple producers one per namespace and consume.

[prakashsaraf7]

So, if I understand correctly, we will have to create multiple consumers, one per namespace and use it for processing? In that case, I suggest correcting the documentation - where it indicates, I can have one consumer for multiple topics spanning across namespaces.

Also, I would appreciate if anyone can provide a technical reason why we have the namespace check? I understand for creating multi-topic partition using "regex" - but if we do have the absolute topic name, what prevents having one consumer for multiple topics (in diff namespace)?

[aahmed-se]

Where in the documentation is this mentioned ?

[prakashsaraf7]

In https://pulsar.apache.org/docs/en/client-libraries-java/
Multiple-Topic Subscriptions section -

"You can also subscribe to an explicit list of topics (across namespaces if you wish):"

[ypt]

+1. I also just ran into this. Reading the docs, I had assumed that I was able to create a consumer that could consume topics across different namespaces, but in trying to do so with the Java client, I'm seeing a java.lang.IllegalArgumentException: Topics should have same namespace exception.

For what it's worth, my usage looks something like the following:

client.newConsumer()
    .topics(listOf(
        "persistent://tenant/namespace-1/topic",
        "persistent://tenant/namespace-2/topic"
    ))

[codelipenghui]

Close this issue via #5716