1. A data capture system for a plant information management system, the data capture system comprising: a data logger ( 2 ) comprising means for interfacing with a process device to receive process data in real time, a database controller ( 4 ) comprising means for storing said data, characterised in that, the database controller comprises means for storing the data in a time-encoded hierarchical object structure ( 3 ) with successive hierarchical levels ( 20 - 23 ) associated with shorter time periods.