Oracle TDE: Observations on Online Encryption, Standby Behaviour, and Crash Recovery
In the modern security landscape, Transparent Data Encryption (TDE) is no longer optional, it is a fundamental requirement for protecting data at rest. While the ALTER TABLESPACE command seems straightforward, the underlying mechanics of how Oracle handles online encryption especially in environments with Data Guard can be surprising. Recently, I’ve been exploring the nuances of online TDE operations. Here are the key takeaways and "gotchas" every DBA should know before hitting 'enter' on that encryption command. 1. The Power of Online Encryption Oracle allows you to encrypt an existing unencrypted tablespace while the database is open and being accessed by users. The syntax is simple: SQL ALTER TABLESPACE TEST ENCRYPTION ONLINE ENCRYPT; Pro Tip: In Oracle 19c, the default algorithm is AES128. If your security standards require AES256, you should set the parameter tablespace_encryption_default_algorithm to 'AES256' or specify it explicitly in yo...