Ksql: Support multiple joins in a single statement

[rmoff]

Currently KSQL only supports single joins in a statement. We should add the ability to join between multiple objects in a single query.

This works:

 select                                                                 \
    d.DocumentName, d.FileExtension, dv.ViewedAt                               \
  from documentViewStream  dv                                           \
  inner join documentTable d                                            \
    on dv.DocumentID = d.DocumentID;

But it would be better if we supported;

select \ u.UserName, d.DocumentName, d.FileExtension, dv.ViewedAt \ from documentViewStream dv \ inner join documentTable d \ on dv.DocumentID = d.DocumentID; inner join userTable u \ on uv.UserID = dv.UserID;

The above query currently throws mismatched input 'inner' expecting ';' (#1612 for improving the message)

In this example it would be a STREAM-TABLE-TABLE join. Currently the workaround would be to resolve the joins separately in multiple queries.

[miguno]

Related to https://github.com/confluentinc/ksql/issues/1532.

[csurepeddi]

I was wondering if this issue has been fixed? If not is there is a timeline on this? thank you

[avanchasr]

@rmoff I have the same scenario. We are getting into KAFKA streams and we have multiple table joins scenario. Any idea on when this will be addressed?

[avanchasr]

+1

[mente]

This would be really great to have multi-joins. Otherwise i have to spam kafka with additional intermediate topics which don't have meanin on it's own and brings headache to our team responsible for kafka cluster :)

[sebastianvaczi]

+1

[reneveyj]

+1 desperately

[Ez2Raven]

+1
reducing the need to create intermediately topics will help in our adoption

[MariamLogvinenko]

+1

[sangvk]

+1. Is this functionality available?

[LampicJ15]

+1

[MichaelDrogalis]

We're starting to work on this. ❤️

[alenpesikan]

In which version of ksqldb will this be published?

[MichaelDrogalis]

@alenpesikan 0.9.0, which will be out in a couple of days.

[mente]

For people not following release version changes by confluent: what does 0.9.0 mean if we have 5.4.1 now?

[MichaelDrogalis]

Here's a quick explanation. We published a version compatibility matrix on Confluent's site. We're going to add a page to ksqldb.io to make the relationship extra clear - it's admittedly a little confusing now.