Explicitly Configuring the Default Cache

You must explicitly configure the size of the default data cache.

Use sp_helpcache to see the amount of memory remaining that can be used for the cache.

For example:

sp_helpcache

Cache Name                Config Size    Run Size        Overhead
-----------------------   -------------  ----------      ----------   
default data cache        50.00 Mb       50.00 Mb        3.65 Mb
pubs_cache                10.00 Mb       10.00 Mb        0.77 Mb

Memory Available For      Memory Configured
Named Caches              To Named Caches
--------------------      ----------------
91.26 Mb                  91.25 Mb

------------------ Cache Binding Information: ------------------ 

Cache Name       Entity Name    Type         Index Name     Status
----------         -----------      -----           ---------        ------

To specify the absolute size of the default data cache, execute sp_cacheconfig with default data cache and a size value. For example, to set the default data cache size to 25MB, enter:

sp_cacheconfig "default data cache", "25M"

When you re-run sp_helpconfig, “Config Value” shows the value.

sp_cacheconfig

Cache Name                Status    Type     Config Value Run Value
------------------------- --------- -------- ------------ ------------
default data cache        Active    Default      25.00 Mb     50.00 Mb
pubs_cache                Active    Mixed        10.00 Mb     10.00 Mb
                                             ------------ ------------
                                      Total      10.00 Mb     60.00 Mb
======================================================================
Cache: default data cache,   Status: Active,   Type: Default
    Config Size: 25.00 Mb,   Run Size: 50.00 Mb
    Config Replacement: strict LRU,   Run Replacement: strict LRU
    Config Partition:            1,   Run Partition:            1

IO Size  Wash Size Config Size  Run Size     APF Percent
-------- --------- ------------ ------------ -----------
    2 Kb 10110 Kb     00.00 Mb    50.00 Mb      10
======================================================================
Cache: pubs_cache,   Status: Active,   Type: Mixed
    Config Size: 10.00 Mb,   Run Size: 10.00 Mb
    Config Replacement: strict LRU,   Run Replacement: strict LRU
    Config Partition:            1,   Run Partition:            1

IO Size  Wash Size Config Size  Run Size     APF Percent
-------- --------- ------------ ------------ -----------
    2 Kb   2048 Kb    0.00 Mb    10.00 Mb    10

Use sp_cacheconfig to change the size of any named cache. Any changes you make to the size of any data cache do not affect the size of any other cache. Similarly, once you specify the size of the default data cache, the configuration of other user-defined caches does not alter the size of the default data cache.

Note: If you configure the default data cache and then reduce max memory to a level that sets the total logical memory value higher than the max memory value, SAP ASE does not start. Edit your configuration file to increase the size of other caches and increase the values of configuration parameters that require memory to create an environment in which total logical memory is higher than max memory.

Explicitly configure the default data cache and all user-defined caches with an absolute value. In addition, many configuration parameters use memory. To maximize performance and avoid errors, set the value of max memory to a level high enough to accommodate all caches and all configuration parameters that use memory.

SAP ASE issues a warning message if you set max memory to a value less than total logical memory.