Scheduling data optimization
You can configure the automatic compressing, shrinking, repacking, and defragmenting of all tables and extents by enabling the auto_crsd Scheduler task.
About this task
Procedure
To enable the auto_crsd task by updating the Scheduler
tables:
- Connect to the sysadmin database as user informix or another authorized user.
- Enable the auto_crsd Scheduler task by using an
UPDATE statement on the ph_task table to set the value of the tk_enable column
to T. For example, the following statement enables the auto_crsd task:
UPDATE ph_task SET tk_enable = 'T' WHERE tk_name = 'auto_crsd';
- Optional:
Change the frequency of when the task is run by running an UPDATE
statement on the ph_task table to change the value of the tk_frequency column.
The default value is 7 00:00:00, which indicates that the task runs
once a week. For example, the following statement changes the frequency
to once a day:
UPDATE ph_task SET tk_frequency = '1 00:00:00' WHERE tk_name = 'auto_crsd';
- Optional: Disable individual operations by
using an UPDATE statement on the ph_threshold table to set
the value column for a threshold to
F
:- AUTOCOMPRESS_ENABLED: controls compression
- AUTOREPACK_ENABLED: controls repacking
- AUTOSHRINK_ENABLED: controls shrinking
- AUTODEFRAG_ENABLED: controls defragmenting
For example, the following statement disables just the defragmentation operation of the auto_crsd task:UPDATE ph_threshold SET value = 'F' WHERE name = 'AUTODEFRAG_ENABLED';
- Optional: Change the thresholds of individual
operations by using and UPDATE statement on the ph_threshold table
to change the value of the value column for a threshold:
- AUTOCOMPRESS_ROWS: The threshold for compression is the number of uncompressed rows. The default threshold is 50 000 rows. A table is compressed when the number of uncompressed rows exceeds 50 000.
- AUTOREPACK_SPACE: The threshold for repacking a table is the percentage of noncontiguous space. The default is 90%. A table is repacked when more than 90% of the space the table occupies is noncontiguous.
- AUTOSHRINK_UNUSED: The threshold for shrinking a table or fragment is the percentage of unused, allocated space. The default is 50%. A table or fragment is shrunk when more than 50% of the allocated space is unused.
- AUTODEFRAG_EXTENTS: The threshold for defragmenting table or fragment extents is the number of extents. The default is 100. A table or fragment is defragmented when the number of extents exceeds 100.
For example, the following statement changes the compression threshold to 5000 rows:UPDATE ph_threshold SET value = '5000' WHERE name = 'AUTOCOMPRESS_ROWS';