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

• 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 (Introduced in v5.0)
  • Extend the statistics feature by collecting the multi-column order dependency information.
  • Refactor the statistics module, including deleting the TopN value from CMSKetch and the histogram, and adding NDV information for histogram buckets of each table index. For details, see descriptions about Statistics - tidb_analyze_version = 2.

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)

Data migration

• DM OpenAPI (Introduced in v5.3)

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)