Browse Prior Art Database

Loading and Updating of Direct Files

IP.com Disclosure Number: IPCOM000076553D
Original Publication Date: 1972-Mar-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Thompson, FD: AUTHOR [+2]

Abstract

Described is a method for faster processing of large, direct disk files when the number of transactions is also large. This objective is achieved without the use of auxiliary cross-reference tables or indexes.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 90% of the total text.

Page 1 of 2

Loading and Updating of Direct Files

Described is a method for faster processing of large, direct disk files when the number of transactions is also large. This objective is achieved without the use of auxiliary cross-reference tables or indexes.

In brief, input records are sorted in ascending order, based on the address of the affected target track in the master file. This is done before the transactions are executed. With this scheme, a random operation is reduced to a nearly sequential one. As a result, disk arm movement and associated processing time involving the master file are reduced.

In the figure, file SETNEW contains the input records, which have fixed length, symbolic keys. The input file is read sequentially, with a new record being created from each one read. The new records are written sequentially to file SETSI (Sort input). Each new record consists of a record read from SETNEW with a relative track address field appended. This track address is generated by a randomizer routine, using the Symbolic Key as input and identifies the target track in the master file to which the transaction is directed. The new records are first sorted on the appended field then written out to file SETSO (Sort Out). At this point, the application program removes the appended field and applies the transaction to the master file, SETP.

Transactions may be record additions, deletions, or modifications. The key idea is that transactions are now ordered by master file relati...