...

1. Forces the checkpoint (required for WAL consistency?)
2. Swap all partition files:
   1. Backup original file.
   2. Move re-encrypted file to the place of the original one.
3. Change encryption key(s) in metastore (update encryption keys history).
4. Remove partition backups (2a).

WAL

After changing the cache encryption key, its entries in the new WAL records will be encrypted with the new key. However, it must be possible to read older WAL records (at least to support historical rebalance).

...