Undo/redo of database files for modifying re-accommodation

Methods, apparatus, and computer program products for modifying re-accommodations. A report characterizing execution of a re-accommodation may be stored in a report database. The report may include an impacted Passenger Name Record (PNR) table that associates each PNR impacted by the re-accommodation with an identifier. The identifier may identify an envelope in a history file comprising a portion of the history file that documents changes made to the PNR by the re-accommodation. In response to receiving a request to modify the re-accommodation, the report may be retrieved from the report database. PNRs impacted by the previous re-accommodation, and changes made to each PNR, may be determined using data in the impacted PNR table and the history files of the PNRs. The impacted PNR table may thereby enable building and execution of a modifying re-accommodation that selectively undoes or redoes a previously executed re-accommodation to implement new solutions to scheduling changes.