Working with Background Encryption Threads

Availabiliity:This feature is Experimental.

Encryption threads in the background allow you to perform some encryption and decryption tasks in real-time.

You would use encryption threads for the following purposes:

  • Encryption threads can encrypt existing tablespaces. Encryption threads allow encryption to be applied to all or some of the existing tablespaces, you can exclude tablespaces from rotation, in a background process. You can encrypt existing tablespaces with the Master key, but you must do this operation by tablespace.
  • Encryption threads encrypt tables with a key from a keyring. The Master key encrypts tables by a key and is stored in the encryption header of the tablespace.
  • Encryption threads allow key rotation. In an encryption thread rotation, the operation re-encrypts each tablespace page by page. The Master key rotation does not re-encrypt each page, only the tablespace encryption header.

If you have tablespaces encrypted with the Master key and you enable encryption threads, the tablespaces are re-encrypted with the keyring key in a background process.


While encryption threads are enabled, you cannot convert the tablespaces to Master key encryption. To convert the tablespaces, you must disable the encryption threads.

Availability:This feature is Experimental quality.
variable innodb_encryption_threads
Command Line:--innodb-encryption-threads
Variable Type:Numeric
Default Value:0

This variable works in combination with the :variable: default_table_encryption variable set to ONLINE_TO_KEYRING. This variable configures the number of threads for background encryption. For the online encryption, the value must be greater than zero.

variable innodb_online_encryption_rotate_key_age
Command Line:--innodb-online-encryption-rotate-key-age
Variable Type:Numeric
Default Value:1

Defines the rotation for the re-encryption of a table encrypted using KEYRING. The value of this variable determines the how frequently the encrypted tables are re-encrypted.

For example, the following values would trigger a re-encryption in the following intervals:

  • The value is 1, the table is re-encrypted on each key rotation.
  • The value is 2, the table is re-encrypted on every other key rotation.
  • The value is 10, the table is re-encrypted on every tenth key rotation.

You should select the value which best fits your operational requirements.

Using Keyring Encryption

Availability:This feature is Experimental quality.

Keyring management is enabled for each table, per file table, separately when you set encryption in the ENCRYPTION clause to KEYRING in the supported SQL statement.



Running an ALTER TABLE ... ENCRYPTION='N' on a table created with ENCRYPTION='KEYRING' converts the table to the existing MySQL schema, tablespace, or table encryption state.