Important

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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

Support collecting statistics for PREDICATE COLUMNS (Introduced in v5.4)
Support synchronously loading statistics. (Introduced in v5.4)
Control the memory quota for collecting statistics. (Introduced in v6.1.0)
Use the thread pool to handle read requests from the storage engine. (Introduced in v6.2.0)
Cost Model Version 2. (Introduced in v6.2.0)
FastScan. (Introduced in v6.2.0)
Extended statistics. (Introduced in v5.0.0)
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).
Background Quota Limiter (Introduced in v6.2.0): You can use the background quota-related configuration items to limit the CPU resources to be used by the background. When a request triggers Quota Limiter, the request is forced to wait for a while for TiKV to free up CPU resources.

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

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)
Cascades Planner: a cascades framework-based top-down query optimizer (Introduced in v3.0)
Table Lock (Introduced in v4.0.0)
ALTER TABLE ... COMPACT (Introduced in v6.1.0)

Storage

Disable Titan (Introduced in v4.0)
Titan Level Merge (Introduced in v4.0)
Divide Regions are divided into buckets. Buckets are used as the unit of concurrent query to improve the scan concurrency. (Introduced in v6.1.0)
TiKV introduces API V2. (Introduced in v6.1.0)

Backup and restoration

Back up and restore RawKV (Introduced in v3.1)

Data migration

Use WebUI to manage migration tasks in DM. (Introduced in v6.0)
Configure disk quota for TiDB Lightning. (Introduced in v6.2.0)
Continuous Data Validation in DM (Introduced in v6.2.0)

Cross-cluster RawKV replication (Introduced in v6.2.0)

Garbage collection

Green GC (Introduced in v5.0)

Diagnostics

SQL diagnostics (Introduced in v4.0)
Cluster diagnostics (Introduced in v4.0)
TiKV-FastTune dashboard (Introduced in v4.0)