1. A method in a parallel database system having a front end server for analyzing queries about a database and a plurality of database operation servers for operating said database, said front end server being connected with said database operation servers by a network, said database operation servers retrieving data from said database, and said front end server processing and controlling retrieved data, said method comprising the steps of: causing a database operation server, upon retrieval of data including a plurality of sub-data items, to return location information about said data as a retrieval result to said front end server; and retrieving said sub-data items of said data from said database operation server based on said location information so that any of said sub-data items in said data is used for processing, control and database operations subsequent to the retrieval of said data.