This topic describes the advanced kernel features supported by PolarDB.

Feature 8.0 5.7 5.6
DOP policy Supported. The version of the kernel must be 8.0.1.1.11 or later. Not supported. Not supported.
Returning Not supported. Supported. The version of the kernel must be 5.7.1.0.6 or later. Not supported.
Instant ADD COLUMN Supported (all versions). Supported. The version of the kernel must be 5.7.1.0.6 or later. Not supported.
Async Metadata Lock Replication Supported. The version of the kernel must be 8.0.1.1.10 or later. Supported (all versions). Supported (all versions).
DDL physical replication optimization Supported. The version of the kernel must be 8.0.1.1.10 or later. Not supported. Not supported.
Parallel DDL Supported. The version of the kernel must be 8.0.1.1.7 or later. Not supported. Not supported.
Fast Query Cache Supported. The version of the kernel must be 8.0.1.1.5 or later. Not supported. Not supported.
Statement Outline Supported. The version of the kernel must be 8.0.1.1.1 or later. Supported. The version of the kernel must be 5.7.1.0.2 or later. Not supported.
ROLLUP Supported. The version of the kernel must be 8.0.1.1.0 or later. Not supported. Not supported.
Recycle bin Supported. The version of the kernel must be 8.0.1.1.2 or later. Not supported. Not supported.
Transparent Data Encryption (TDE) Supported. The version of the kernel must be 8.0.1.1.1 or later. Supported. The version of the kernel must be 5.7.1.0.3 or later. Supported. The version of the kernel must be 5.6.1.0.21 or later.
Parallel query Parallel query Supported. The version of the kernel must be 8.0.1.0.5 or later. Not supported. Not supported.
Hash joins in parallel queries Supported. The version of the kernel must be 8.0.2.1.0 or later. Not supported. Not supported.
Perform semijoins in parallel Supported. The version of the kernel must be 8.0.1.1.2 or later. Not supported. Not supported.
Parallel Hint Supported. The version of the kernel must be 8.0.1.0.5 or later. Not supported. Not supported.
High concurrency optimization Statement Concurrency Control Supported. The version of the kernel must be 8.0.1.1.7 or later. Not supported. Supported. The version of the kernel must be 20200601 or later.
Inventory Hint Supported. The version of the kernel must be 8.0.1.1.1 or later. Not supported. Not supported.
Statement Queue Supported. The version of the kernel must be 8.0.1.1.1 or later. Not supported. Supported. The version of the kernel must be 20200616 or later.
Hot row optimization (applicable to flash sales) Supported. The version of the kernel must be 8.0.1.1.10 or later. Not supported. Supported. The version of the kernel must be 20200601 or later.
Thread pool Supported. The version of the kernel must be 8.0.1.1.1 or later. Not supported. Supported. The version of the kernel must be 20200423 or later.