Discussion for deleting garbage data in StateDB

[ethan-kr]

This issue was written for the development of StateDB's garbage data deletion feature.

In StateDB, dozens to thousands of data are updated every block, and that much garbage data is created. There are state migration methods, but they increase the IO load and put a lot of strain on the system.

We want to develop a method to minimize the load on the system by putting the data to be deleted in a queue and clearing it little by little.

This issuance number is used as the KIP number.