kafka.common.Topic shows that currently period is a valid character and I
have verified I can use kafka-topics.sh to create a new topic with a period.
AdminUtils.createOrUpdateTopicPartitionAssignmentPathInZK currently uses
Topic.validate before writing to Zookeeper.
Should period character support be removed? I was under the same impression
as Gwen, that a period was used by many as a way to "group" topics.
The code is pasted below since its small:
object Topic {
val legalChars = "[a-zA-Z0-9\\._\\-]"
private val maxNameLength = 255
private val rgx = new Regex(legalChars + "+")
val InternalTopics = Set(OffsetManager.OffsetsTopicName)
def validate(topic: String) {
if (topic.length <= 0)
throw new InvalidTopicException("topic name is illegal, can't be
empty")
else if (topic.equals(".") || topic.equals(".."))
throw new InvalidTopicException("topic name cannot be \".\" or
\"..\"")
else if (topic.length > maxNameLength)
throw new InvalidTopicException("topic name is illegal, can't be
longer than " + maxNameLength + " characters")
rgx.findFirstIn(topic) match {
case Some(t) =>
if (!t.equals(topic))
throw new InvalidTopicException("topic name " + topic + " is
illegal, contains a character other than ASCII alphanumerics, '.', '_' and
'-'")
case None => throw new InvalidTopicException("topic name " + topic +
" is illegal, contains a character other than ASCII alphanumerics, '.',
'_' and '-'")
}
}
}
On Fri, Jul 10, 2015 at 2:50 PM, Todd Palino <tpal...@gmail.com> wrote:
> 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
> >
>
--
Grant Henke
Solutions Consultant | Cloudera
ghe...@cloudera.com | twitter.com/gchenke | linkedin.com/in/granthenke
