You can configure the automatic compressing, shrinking,
repacking, and defragmenting of all tables and extents by enabling
the auto_crsd Scheduler task.
You can enable and configure the auto_crsd task by updating Scheduler tables in the sysadmin database.
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';
When a threshold for an operation that you enabled is exceeded,
the Scheduler runs the operation.