TiDB Experimental Features

This document introduces the experimental features of TiDB in different versions. It is NOT recommended to use these features in the production environment.

Performance

• Automatically scale TiFlash thread pool. (Introduced in v5.4)
• Raft Engine. (Introduced in v5.4)
• Support collecting statistics for PREDICATE COLUMNS (Introduced in v5.4)
• Support synchronously loading statistics. (Introduced in v5.4)
• Randomly sample about 10000 rows of data to quickly build statistics (Introduced in v3.0)

Stability

• Improve the stability of the optimizer's choice of indexes: extend the statistics feature by collecting the multi-column order dependency information (Introduced in v5.0).

Scheduling

Elastic scheduling feature. It enables the TiDB cluster to dynamically scale out and in on Kubernetes based on real-time workloads, which effectively reduces the stress during your application's peak hours and saves overheads. See Enable TidbCluster Auto-scaling for details. (Introduced in v4.0)

SQL

• Use SQL interface to set placement rules for data (Introduced in v5.3)
• List Partition (Introduced in v5.0)
• List COLUMNS Partition (Introduced in v5.0)
• Dynamic Pruning Mode for Partitioned Tables. (Introduced in v5.1)
• The expression index feature. The expression index is also called the function-based index. When you create an index, the index fields do not have to be a specific column but can be an expression calculated from one or more columns. This feature is useful for quickly accessing the calculation-based tables. See Expression index for details. (Introduced in v4.0)
• Generated Columns (Introduced in v2.1)
• User-Defined Variables (Introduced in v2.1)
• JSON data type and JSON functions (Introduced in v2.1)
• Using ALTER TABLE to modify multiple columns or indexes (Introduced in v5.0.0)
• Cascades Planner: a cascades framework-based top-down query optimizer (Introduced in v3.0)
• Table Lock (Introduced in v4.0.0)

Configuration management

• Persistently store configuration parameters in PD, and support dynamically modifying configuration items. (Introduced in v4.0)

Data sharing and subscription

• Integrate TiCDC with Kafka Connect (Confluent Platform) (Introduced in v5.0)

Storage

• Disable Titan (Introduced in v4.0)
• Titan Level Merge (Introduced in v4.0)

Backup and restoration

• Back up Raw KV (Introduced in v3.1)

Garbage collection

• Green GC (Introduced in v5.0)

Diagnostics

• SQL diagnostics (Introduced in v4.0)
• Cluster diagnostics (Introduced in v4.0)
• Continuous profiling (Introduced in v5.3)
• Online Unsafe Recovery (Introduced in v5.3)
• Top SQL (Introduced in v5.4)