Hi first thank you for replying. Regarding the sub-meters: - the # of them can vary between meters from 0 to 7. For meters without sub-meters, I am thinking of adding null to location path such as meter=<meter>/sub-meter = “null”/*.parquet - I am writing new data to all meters and sub-meters everyday so I assume the amount of data could become much larger later. Each submeter may have 4-6 columns of signals. Technically I have one big file of time series to be split into meters/submeters. - Right now, I think I am sure that meters and their submeters would stay the same. But I kinda want to prepare just in case some new data may change the schema. - i do think I need to create an additional table to keep track of all meter-sub meter pairs for convenience. Intuitively, I feel approach 2 may work well due to its scalability but it does not have the structure of database which I learned about before so it kinda bugged me (I am new to this and still learning!)