As of version 3.9.0 all future indexes will use 64-bit hashes instead of 32-bit hashes. The system will automatically transition from 32-bit to 64-bit by writing all new indexes as 64-bit indexes during the merge process.
If you prefer to use only 64-bit indexes immediately you can force this. For a small database, delete the index folder and let it rebuild (this might take a while)
If you have a large database, remote storage, etc and cannot lose downtime, you can do this operation offline on another node with the following steps:
For other indices, you index will eventually become 64 bit due to the merging process that occurs over time.