HP NonStop G-Series - Manual (Page 258)

Compressing Space in an EDIT File
Handling Your EDIT Files
6–8 058061 Tandem Computers Incorporated
Compressing Space in
an EDIT File
EDIT makes EDIT files recoverable from process failures. To do this
recovery, EDIT copies the modified lines of text into a new area in the disk
file as you make modifications to an EDIT file. EDIT can reuse portions of
the disk file that have been obsoleted as a result of editing. However,
portions of the file that are obsolete often remain on disk, taking up space.
To determine the percentage of an EDIT file that is unused, you use the
QUERY command. If the unused portion (SLACK) is greater than 40%, you
should use two PUT commands to compress the file. The first PUT
command compresses the file. The second PUT command maximizes the
compression. For example:
*QUERY
FILE $WORK.FICTION.POEMS, ...
...
SPACE USED 53248/ 393216 SLACK 58%
*PUT !
*QUERY
FILE $WORK.FICTION.POEMS, ...
...
SPACE USED 22528/ 229376 SLACK 5%
*PUT !
*QUERY
FILE $WORK.FICTION.POEMS, ...
...
SPACE USED 22528/ 98304 SLACK 5% Use this command to see if
the SLACK exceeds 40%.
After one PUT command,
the SPACE USED and
SLACK are reduced.
Use this command
to compress the file.
Use this command again
to compress the file.
After two PUT commands,
the SPACE USED is
reduced even more.
For more information and examples, see the PUT and QUERY commands in
Section 4.