We are working on updating this book for the latest version. Some content might be out of date.
Currently, it is not possible to change the
similarity mapping for an
existing field. You would need to reindex your data in order to do that.
Create a custom similarity called
Disable field-length normalization. See Tuning BM25.
A custom similarity can be updated by closing the index, updating the index settings, and reopening the index. This allows you to experiment with different configurations without having to reindex your documents.