Browse Prior Art Database

Serializing the Extension of a Data File in OS/2 Database Manager

IP.com Disclosure Number: IPCOM000108492D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 31K

Publishing Venue

IBM

Related People

Rodriguez, RA: AUTHOR [+2]

Abstract

Disclosed is a method for serializing the extension of a data file in OS/2* Database Manager.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Serializing the Extension of a Data File in OS/2 Database Manager

       Disclosed is a method for serializing the extension of a
data file in OS/2* Database Manager.

      An algorithm that guarantees data consistency for information
kept in the data file header control record and allows other
applications to access the data records contained on the same page as
the data file header control record is described.

      The data file control record keeps track of the total number of
pages in a particular data file.  This record is contained on the
first page of the data file along with other data records.

      The information in the data file header control record is used
to determine how many pages are available in the data file and what
the next page number will be when the file is extended.

      When it is determined that the file must be extended, an
exclusive lock is attained on the data file header control record,
the data file is extended, the page count is updated in the data file
header control record, and the exclusive lock is released.

      By allowing only one application to extend the data file at a
time, it is guaranteed that the page count kept in the data file
header control record is accurate.  This method does not prevent
other applications from accessing data records kept on the same page.
*  Trademark of IBM Corp.