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Restoring Database Pages Disclosure Number: IPCOM000104885D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 76K

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Bracht, CJ: AUTHOR [+2]


A method of restoring database files that have been spanned is described here.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Restoring Database Pages

      A method of restoring database files that have been spanned is
described here.

      In prior releases, the OS/2* Database Manager Backup and
Restore Utilities used the operating system backup and restore
functions.  This was possible because all files of the database were
created in one directory.

      With the new release, database files can be spanned across many
different directories.  Each database object is no longer guaranteed
to be contained in a single file.  So, the Backup Utility now backs
up database table objects (data, index, and long field) 4K page by 4K
page.  It uses existing buffer pool interfaces to read the pages of
each object.

      The utility also backs up non-table object files that are part
of the database such as the database configuration file, the log
control file, and the object relocation file (ORF).  The ORF contains
an entry for each table object contained in the database.  Each entry
defines the location of each of the object's files or parts.

      The Restore Utility needs to restore each database object into
the appropriate set of directories.  However, the utility has no
means of knowing where the parts of each table object belong or how
the data is distributed among the parts.  This knowledge is isolated
in the buffer pool component.  Restore cannot use the existing buffer
pool interfaces for creating objects and writing pages because the
utility must be connected to the database to use them.  And of course
it can't connect to the database if it doesn't exist.

      The Restore Utility copies all database files that cannot be
spanned into the main database directory from the backup media.  A
new set of buffer pool interfaces is provided to create the ORF in
the main database directory, create table objects, populate table
objects, and to close table object files.  These interfaces do not
depend on the database being initialized like the existing