What limitations exist when naming a datasource, dimension and metric?


I’ve read through the documentation and can’t seem to find what, if any, limitations there are on names for datasource, dimensions or metrics.

Looks like they must be UTF-8 strings and they are case sensitive since version 0.7, but that is as much as I have been able to figure out.

It is certainly possible that I missed something in the docs, if so, I apologize for the noise. :slight_smile:

For the solution we have built around Druid, we are interested in knowing:

  • what characters are allowed (or prohibited) in the names?
  • what is the maximum length of a dimension, metric name or datasource?

Thanks in advance,


Hi Patrick,

They need to be utf-8 strings and they need to be filesystem-safe, since they will be used as the names of files on disk. So they at least must not include slashes. Beyond that the specifics depend on the filesystem you are using (and the deep storage you are using). The maximum lengths are also going to be more related to filesystem limits than any limit imposed by Druid itself.