# Chapter Objectives
+ Understand the parameter system of the TiDB database
+ Understanding the parameter scope of the TiDB database
+ Ability to modify TiDB database parameters via command line and configuration files
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The first part is the TiDB system variable. This system variable can be modify by the MySQL client. The system variable specifically refers to the configuration of the TiDB-Server component, excluding the PD and TiKV configurations, which are persisted in the database store.