# Additional Knowledge: Dml Data Writing Process


![left](./student-guide/diagram/03-10-1.png)

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Write process: The user's SQL is read by the Protocol Layer, and TSO is obtained on the PD. So the first step is to confirm if there is a problem with the PD that causes the SQL to be slow, the second step is to confirm whether there is a problem with parse and compiling, and the third step to confirm that there is no problem