Yeah, if your field contains a list it won't be aggregatable in Kibana. You need to find a way to normalize your data without the list, at the same time keeping the relevancy for your use case.
The format that i'm thinking about is something like this:
I don't really know exactly how elasticsearch optimizes this, but I know it's smart and it won't increase the disk size as much as we'd think and this format makes all the data searchable and aggregatable. You can get pretty much anything from a format like that:
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.