As outlined in , support for null tokens can be problematic in some situations.

It can trigger:

• analysis issues (when querying on a null token, you probably don't want your query to be analyzed)
• mapping issues (see HSEARCH-2389 Open or HSEARCH-2415 Open )

As Sanne Grinovero suggested in HSEARCH-2389 Open , a better solution might be to implement "exists" queries. They already exist in Elasticsearch, and maybe we could implement them easily with recent Lucene versions.