add skip empty generations

[katherine91]

In table system_distributions.cdc_streams_descriptions_v2 in our scylla db one of generations gives empty streams i.e. generation exists in cdc_generations_timestamps, but when querying cdc_streams_descriptions_v2 with where time = 'missing timestamp' gives 0 rows.
Cdc does not run, gives IllegalArgumentException, because https://github.com/scylladb/scylla-cdc-java/blob/master/scylla-cdc-base/src/main/java/com/scylladb/cdc/model/master/GenerationMetadata.java#L21
Is it possible to skip empty generations or provide start date that is not equal to Date(0) - epoch start

[dkropachev]

@katherine91 , thanks for reporting it, we will fix it ASAP

[Bouncheck]

@katherine91 can you share how did you arrive at this situation or contents of those system tables? While this issue probably can be handled it strikes me as odd that some generation has 0 streams.

[katherine91]

@katherine91 can you share how did you arrive at this situation or contents of those system tables? While this issue probably can be handled it strikes me as odd that some generation has 0 streams.

Our database admin says it's due to system_distributions keyspace replication. This error appeared in prod cluster while test cluster worked well. Eventually our admin did something with scylla cluster, so that the generation that had no streams now has streams in system_distributions.cdc_streams_descriptions_v2 table and error gone. Don't know if someone else also has or will have same problem with scylladb cluster. If it helps our scylladb cluster is on 2 dc with 3 nodes each. And generation with empty streams created way before, but we started cdc only now, so we even don't need to check previous generations if it has left cdc records.