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Table Storage Architecture for the OS/2 Extended Edition Database Manager

IP.com Disclosure Number: IPCOM000036461D
Original Publication Date: 1989-Oct-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 4 page(s) / 102K

Publishing Venue

IBM

Related People

Allan, AL: AUTHOR [+3]

Abstract

This disclosure describes a physical storage system for base tables in a relational database manager built for the OS/2* operating system. Base tables are relations whose data is stored permanently in a disk-oriented file system. Base tables can have B-tree indexes associated with them to improve access speed. Each column of a base table has a data type, and a value (perhaps null) exists in that column for each row of the table. One of the data types supported in conventional relational systems is a variable length byte stream which can be up to 32K bytes in length. These types of data values are called long fields.

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Table Storage Architecture for the OS/2 Extended Edition Database Manager

This disclosure describes a physical storage system for base tables in a relational database manager built for the OS/2* operating system. Base tables are relations whose data is stored permanently in a disk-oriented file system. Base tables can have B-tree indexes associated with them to improve access speed. Each column of a base table has a data type, and a value (perhaps null) exists in that column for each row of the table. One of the data types supported in conventional relational systems is a variable length byte stream which can be up to 32K bytes in length. These types of data values are called long fields.

Some relational systems implement their own file management subsystem to handle base tables, indexes, and long field data, rather than relying on the underlying operating system. A common reason for this is that the file system access methods and buffer caching in generalized operating systems are not usually optimum for the type of accesses which are common in relational systems. The drawback to this approach is that the configuration and installation of the database manager is much more complex, and disk space must be dedicated to the database manager.

The configuration, installation, and maintenance of a private file system can be a difficult task, and one not well-suited to the general user of a personal computer system. A database manager for a personal computing system like OS/2 does not have a user community well-suited to these kinds of complex configuration and installation tasks. Therefore, it is important for ease-of-use reasons that the physical storage for the database manager be integrated with the OS/2 file system, as described below. OS/2 Database Manager Base Table Storage

A base table for the IBM OS/2 Extended Edition Database Manager consists of up to three OS/2 files. One file contains the rows of data comprising the table. The second file contains all of the table's indexes (there can be multiple indexes on a table). The third file contains the table's long fields. If the base table has no indexes or long fields, those files are not created. Storing rows, indexes, and long fields in separate files allows for storage management and access techniques in each file type to be uniquely suited to the kind of data it contains.

The file architecture allows for more than one table to be "clustered" into the same set of three files. All the tables which are clustered share the same data file, index file, and long field file. This capability is provided to allow physically contiguous placement of tables which are commonly used together in order to minimize I/O and reduce the amount of OS/2 resources used for open files.

The three independent files are managed by a single Data Manager component which externalizes them to other system components as unified, logical data objects called tables. Row File

The row file exists as long as, at le...