I had to go look this one up again to make sure - https://issues.apache.org/jira/browse/KAFKA-495
The only valid character names for topics are alphanumeric, underscore, and dash. A period is not supposed to be a valid character to use. If you're seeing them, then one of two things have happened: 1) You have topic names that are grandfathered in from before that patch 2) The patch is not working properly and there is somewhere in the broker that the standard is not being enforced. -Todd On Fri, Jul 10, 2015 at 12:13 PM, Brock Noland <br...@apache.org> wrote: > On Fri, Jul 10, 2015 at 11:34 AM, Gwen Shapira <gshap...@cloudera.com> > wrote: > > Hi Kafka Fans, > > > > If you have one topic named "kafka_lab_2" and the other named > > "kafka.lab.2", the topic level metrics will be named kafka_lab_2 for > > both, effectively making it impossible to monitor them properly. > > > > The reason this happens is that using "." in topic names is pretty > > common, especially as a way to group topics into data centers, > > relevant apps, etc - basically a work-around to our current lack of > > name spaces. However, most metric monitoring systems using "." to > > annotate hierarchy, so to avoid issues around metric names, Kafka > > replaces the "." in the name with an underscore. > > > > This generates good metric names, but creates the problem with name > collisions. > > > > I'm wondering if it makes sense to simply limit the range of > > characters permitted in a topic name and disallow "_"? Obviously > > existing topics will need to remain as is, which is a bit awkward. > > Interesting problem! Many if not most users I personally am aware of > use "_" as a separator in topic names. I am sure that many users would > be quite surprised by this limitation. With that said, I am sure > they'd transition accordingly. > > > > > If anyone has better backward-compatible solutions to this, I'm all ears > :) > > > > Gwen >
