Why does the data length shown by `information_schema.tables.data_length` differ from the store size on the TiKV monitoring panel?

Two reasons:

  • The two results are calculated in different ways. information_schema.tables.data_length is an estimated value by calculating the averaged length of each row, while the store size on the TiKV monitoring panel sums up the length of the data files (the SST files of RocksDB) in a single TiKV instance.
  • information_schema.tables.data_length is a logical value, while the store size is a physical value. The redundant data generated by multiple versions of the transaction is not included in the logical value, while the redundant data is compressed by TiKV in the physical value.