ElasticsearchIndexMappingResolver

The mapping of an index, cached per index until refresh.

Wow creates an aggregate's index on its first write, from the index templates, so until then the index does not exist. Its mapping is then the one the index will be created with: the matching index templates' mapping, as Elasticsearch simulates it for the name (_index_template/_simulate_index), or no field at all when no template matches. That mapping is provisional and never cached: the next load reads the index once it exists, with the fields of the templates plus the ones its documents added. Simulating needs the manage_index_templates cluster privilege, which initializing Wow's templates (wow.elasticsearch.auto-init-template) needs as well.