I'd like to add some validation on my side for field names before indexing documents into elsaticsearch. However, I cannot find any documentation describing what is an invalid field name. The only thing I found was this old discussion from 2014, describing the following:
There are also some restrictions on type names for mappings:
- must not start with underscore "_"
- must not contain comma ","
- must not contain hash mark "#"
- usage of point "." is discouraged but possible
Are these still valid?