Method and apparatus for continuous after-imaging

Claim 1

In a distributed transaction data base processing system for concurrent data base entries for executing transactions with cause a stored data base file to be updated, including a stored data base file, a temporary storage file, and a permanent storage medium in communication with said temporary storage file a method for executing transactions which cause said stored data base file to be updated comprising the steps of: storing on a temporary basis in an after-image temporary storage file after-image data representative of the state of data base file entries after an update has occurred; storing in an after-image permanent storage medium associated with said after-image temporary storage file after-image data representative of the state of data base file entries after an update has occurred; writing after-image update data into said temporary storage file; initiating transfer of said after-image update data from said temporary storage file to said permanent storage medium prior to said temporary file becoming filled with data; identifying with an end pointer a temporary storage file location at which said transfer step is initiated for transferring after-image update data records from the temporary storage file to the permanent storage medium; comparing the location at which a present after-image update record is being written with the location identified by the write pointer; and automatically transferring on a continuous time-shared basis the after-image update data in the temporary storage file when the record being written is being written at lest in part in a location past the location identified by said write pointer, so that transferring occurs in an ongoing time-shared basis with other ongoing operations of said distributed transaction processing system.