# SQL Plan Management (SPM)
+ Key features provided by SPM:
  + SQL binding: Specify an execution plan for a query without modifying the SQL statement
  + Baseline capturing: Specify the acceptable execution plans for a query
  + Baseline evolution: Add better execution plans to the baseline
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SQL Plan Management consists of a set of features that allow for manual intervention in SQL execution plans through SQL bindings. These features include SQL binding, baseline capturing, and baseline evolution.

SQL Binding:
With SQL bindings, you can choose a specified execution plan without altering the SQL statements themselves.  
For more details, visit: https://docs.pingcap.com/tidb/stable/sql-plan-management#sql-binding

Baseline Capturing:
A plan baseline is a collection of approved plans that the optimizer can use to execute a SQL statement. Typically, TiDB includes a plan in the baseline only after confirming its performance is satisfactory. In this context, a plan comprises all necessary plan-related details, such as the SQL plan identifier, hint set, bind values, and optimizer environment, which the optimizer needs to reproduce an execution plan.  
For more details, visit: https://docs.pingcap.com/tidb/stable/sql-plan-management#baseline-capturing

Baseline Evolution:
As data changes, the previously bound execution plan may no longer be optimal. The baseline evolution feature can automatically refine the bound execution plan. Moreover, baseline evolution can mitigate the impact of statistical information changes on execution plans to some extent. It is important to note that baseline evolution is an experimental feature and may pose unknown risks. Therefore, its use is not recommended in production environments.  
For more details, visit: https://docs.pingcap.com/tidb/stable/sql-plan-management#baseline-evolution

In this lesson, we will concentrate on SQL bindings. Baseline capturing and evolution will be introduced in the system optimization section.