Decrypt InnoDB Tables

Procedure to decrypt InnoDB tables by setting `innodb_encrypt_tables=OFF` and executing `ALTER TABLE ... ENCRYPTION='N'`.

When data-at-rest encryption is enabled, InnoDB tables and tablespaces are transparently encrypted and decrypted by the storage engine. In some cases, administrators may need to decrypt an InnoDB table—for example, when migrating data to an environment where encryption is not required, or when disabling encryption to simplify configuration.

For more information, refer to, MDEV-17269.

Decrypting a Table

To decrypt a specific InnoDB table, use the ENCRYPTION clause with ALTER TABLE:

ALTER TABLE mydb.mytable ENCRYPTION='N';

This statement rewrites the table in an unencrypted format.

• If the table is stored in a file-per-table tablespace, the corresponding .ibd file is decrypted and rewritten.

• If the table resides in the system tablespace, the data is also rewritten unencrypted.

Decrypting All Tables in a Schema

To decrypt all tables in a schema, you can generate and run ALTER TABLE statements programmatically:

SELECT CONCAT('ALTER TABLE ', table_schema, '.', table_name, ' ENCRYPTION="N";')
FROM information_schema.tables
WHERE engine='InnoDB'
  AND table_schema='mydb';

Copy and execute the generated statements.

Verifying Decryption

After decryption, you can verify the encryption status of a table with:

SELECT table_name, create_options
FROM information_schema.tables
WHERE table_schema='mydb';

If the table is unencrypted, the create_options column will not include ENCRYPTION="Y".