Important

You are viewing the documentation of an older version of the TiDB database (TiDB v4.0).

It is recommended that you use the latest LTS version of the TiDB database.

SQL Logical Optimization

This chapter explains some key logic rewrites to help you understand how TiDB generates the final query plan. For example, when you execute the select * from t where t.a in (select t1.a from t1 where t1.b=t.b) query in TiDB, you will find that the IN sub-query t.a in (select t1.a from t1 where t1.b=t.b) does not exist because TiDB has made some rewrites here.

This chapter introduces the following key rewrites:

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