Dictionary compression is generally used.
The other compression types are activated or modified in the following scenarios:
|Auto merge, critical merge, smart merge||
Whenever a merge of these types is executed, an optimized compression of the new main storage is identified and implemented. See SAP Note 2057046 for more information about merge types.
As an exception the compression of RANGE partitioned tables may not be optimized during these merges. See SAP Note 2105761 for more information.
|Mergedog||The mergedog can trigger compression optimizations in background.|
|Manual compression optimization||
The following commands can be used to trigger compression optimizations manually:
UPDATE "<table_name>" WITH PARAMETERS ('OPTIMIZE_COMPRESSION' = 'YES') UPDATE "<table_name>" WITH PARAMETERS ('OPTIMIZE_COMPRESSION' = 'FORCE')
The first variant triggers a check for a recompression. The actual recompression will only be done if certain prerequisites are fulfilled.
The 'FORCE' variant makes sure that a compression optimization is executed in any case.