# Target Column Read-Only Scenario 

+ Without an ADD INDEX operation:
+ When there is an ADD INDEX operation and tidb_ddl_reorg_batch_size = 32:


![left](./student-guide/diagram/19-Read-only-scene-01-01.png)

![right](./student-guide/diagram/19-Read-only-scene-01-02.png)

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550.9
8812.8