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Mapping a Relational Database to a Hierarchical File System

IP.com Disclosure Number: IPCOM000116653D
Original Publication Date: 1995-Oct-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 4 page(s) / 125K

Publishing Venue

IBM

Related People

Yanker, PC: AUTHOR

Abstract

As multimedia data accumulates in computers and networks around the world, it becomes more and more important to be able to organize and store the data inside the data bases. The desire to store multimedia data inside the database requires the invention of non-traditional data types such as image, video and audio. Two approaches have been used to accomplish this: o Store the file name in a data base field and keep the file in the file system. o Store the file inside the data base in a very large field called a Binary Large Object (BLOB).

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 42% of the total text.

Mapping a Relational Database to a Hierarchical File System

      As multimedia data accumulates in computers and networks around
the world, it becomes more and more important to be able to organize
and store the data inside the data bases.  The desire to store
multimedia data inside the database requires the invention of
non-traditional data types such as image, video and audio.  Two
approaches have been used to accomplish this:
  o  Store the file name in a data base field and keep the file in
the
      file system.
  o  Store the file inside the data base in a very large field called
      a Binary Large Object (BLOB).

      The first approach allows existing legacy programs such as
browsers to continue accessing files, but suffers from lack of
referential integrity from the data base point of view.  The second
approach preserves the referential integrity but requires existing
programs to be modified to access the stored data base.

      This invention allows files, such as multimedia files, to be
stored inside a database, for example as a BLOB, for referential
integrity, but still appear to be a file in the file system.  This is
accomplished by mapping the fixed hierarchy of the database to the
hierarchy of the file system.

      Simple data base queries can be performed using existing file
system knowledge.  This capability is especially useful for
multimedia files as many special access and storage routines have
already been implemented for them using file systems.

Relational database systems are typically organized with the
following hierarchy:
    Database->Qualifier->Table->Column->Row
  whereas many file systems have hierarchies that represent directory
structures.  If the database hierarchy is mapped onto a file system
hierarchy, then any field within a database can be accessed as if it
were a fully qualified path.  In Unix the path becomes:
    /dbfs/Database/Qualifier/Table/column/field

In DOS, Windows* and OS/2** it is:
    q:\dbfs\database\qualifier\table\column\field
  dbfs/ and q:bfs\ are used as special data base file system
   identifiers.

      Thus, a field within a column can be uniquely identified by
both the file system and the data base.  If the field is BLOB, then
the data in the BLOB can be accessed from both the file and the
database table.

      For example, suppose there is an Employee Table 1 within a
database named FASHION and qualified by FTVSYS:
  TABLE 1.  Employee Table
  NAME          SALARY              FACE          PICTURE
  George        100,000          <fgeorge.bmp>    <george.tif>
  Sam           300,000          <fsam.bmp>       <sam.bmp>
  Tom           200,000          <ftom.bmp>       <tom.gif>

FACE and PICTURE are database columns of type multimedia image BLOB,
and the notation <george.bmp> indicates that the field contains th...