By default, Sybase IQ sets the size of the main and temporary buffer caches to 16MB and 12MB respectively. Most applications will require much higher values (limited by the total amount of physical memory). See the preceding sections to determine the right settings for your system.
Once you know what settings you need, use the options described in Table 12-2 to set buffer cache sizes. You may also use the options described in Table 12-3 to make more memory available for buffer caches.
Method |
When to use it |
How long the setting is effective |
For more information, see |
|---|---|---|---|
-iqmc and -iqtc server switches |
Recommended method. Sets cache sizes when the database and server are not running. Allows cache sizes >4GB. Especially useful for 64-bit platforms, or if cache size database options are set larger than your system can accommodate. |
From the time the server is started until it is stopped |
“Setting buffer cache size server switches” on page 521 |
MAIN_CACHE_MEMORY_MB and TEMP_CACHE_MEMORY_MB database options |
Set buffer cache sizes up to 4GB. Database must be open to set these values. This method is not recommended. |
From the next time the database is restarted until you reset these options, or override them with server switches |
“Database Options” chapter of Sybase IQ Reference Manual |
Method |
When to use it |
How long the setting is effective |
For more information, see |
|---|---|---|---|
-iqwmem server switch |
Use on some UNIX platforms to provide additional memory for use as buffer caches. They do not actually set the cache sizes. |
From the time the server is started until it is stopped |
“Platform-specific memory options” on page 526 |
LOAD_MEMORY_MB database option |
Indirectly affects buffer cache size, by controlling the memory that can be used for loads. On some platforms, allowing unlimited memory for loads means less memory is available for buffer caches. |
Immediately until you reset the option |
“Memory for loads, inserts, updates, synchronizations, and deletions” |
