as follows:
1. Convenient sorting and search
2. Improve readability and clearly see the unique identification of each row of data
3. Improve query performance, such as prefix indexing and other scenarios: https://doris.apache.org/zh-CN/docs/data-table/index/index-overview?\_highlight=%E5%89%8D%E7%BC%80#%E5%89%8D%E7%BC%80%E7%B4%A2%E5%BC%95