1. A method comprising: maintaining a source file version table including: source data file information for data loading of a plurality of source data files, wherein the source data files are .xml files; current version information for each of the source data files; and maximum version information for each of the source data files with respect to maximum version numbers used in the past; maintaining a plurality of individual data base (DB) tables each of which includes creation version information for each record of each source data file; maintaining a system table containing system information of the DB tables, including pending status and creation time of the DB tables; performing update, undo, and redo operations of data loading using the source file version table and the DB tables, wherein the data loading includes splitting each of the source data files into multiple blocks, and loading the multiple blocks in a bulk loading operation; tracking a tuple count and match the tuple count between the DB tables; matching a plurality of keys between the DB tables; aborting the data loading after a partial completion of the data loading, and resuming the data loading without restarting to a beginning of the data loading; tracking incomplete records in the information warehouse using a state transition diagram which diagrams load progress states of the multiple blocks in the information warehouse; removing all the tracked incomplete records in the information warehouse; determining whether a modification has been made to one of the source data files; and deleting a non-current version of one of the DB tables after the undo operation in response to determining that a modification was made to said one of the source data files.