MySQL Server supports a keyring that enables internal server components and plugins to securely store sensitive information for later retrieval. See Section 8.4.5, “The MySQL Keyring”.
          The keyring_keys table exposes
          metadata for keys in the keyring. Key metadata includes key
          IDs, key owners, and backend key IDs. The
          keyring_keys table does
          not expose any sensitive keyring data
          such as key contents.
        
          The keyring_keys table has these
          columns:
- KEY_ID- The key identifier. 
- KEY_OWNER- The owner of the key. 
- BACKEND_KEY_ID- The ID used for the key by the keyring backend. 
          The keyring_keys table has no
          indexes.
        
          TRUNCATE TABLE is not permitted
          for the keyring_keys table.