But it looks like I can only use boolean, dates and number.
That should only be true of the metric part (the count), not the dimension part (the way you are grouping the data). You can group on the string values in that field, basically just split the slices by "terms" on that field. Leave the metric as "count" and you should get what you want.
Apache, Apache Lucene, Apache Hadoop, Hadoop, HDFS and the yellow elephant
logo are trademarks of the
Apache Software Foundation
in the United States and/or other countries.