A technique performs file-based time series management. The technique involves initiating a recordation operation that records a source-provided time series in rows of a row-formatted file. The technique further involves, after the recordation operation is initiated, encountering a conversion event. The technique further involves, in response to encountering the conversion event, performing a conversion operation that converts the source-provided time series recorded in the rows of the row-formatted file into a file-provided time series and saving the file-provided time series in columns of a column-formatted file.