#include <db_cxx.h>

int
DbMpoolFile::set_priority(DB_CACHE_PRIORITY priority);

int
DbMpoolFile::get_priority(DB_CACHE_PRIORITY *priorityp);

Description: DbMpoolFile::set_priority

Set the cache priority for pages from the specified file. The priority of a page biases the replacement algorithm to be more or less likely to discard a page when space is needed in the buffer pool. The bias is temporary, and pages will eventually be discarded if they are not referenced again. The DbMpoolFile::set_priority method is only advisory, and does not guarantee pages will be treated in a specific way.

To set the priority for the pages belonging to a particular database, call the DbMpoolFile::set_priority method using the DbMpoolFile handle returned by calling the Db::get_mpf method.

The DbMpoolFile::set_priority method configures a file in the memory pool, not only operations performed using the specified DbMpoolFile handle.

The DbMpoolFile::set_priority method may be called at any time during the life of the application.

The DbMpoolFile::set_priority method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success.

Parameters

priority

The priority parameter must be set to one of the following values:

DB_PRIORITY_VERY_LOW

The lowest priority: pages are the most likely to be discarded.

DB_PRIORITY_LOW

The next lowest priority.

DB_PRIORITY_DEFAULT

The default priority.

DB_PRIORITY_HIGH

The next highest priority.

DB_PRIORITY_VERY_HIGH

The highest priority: pages are the least likely to be discarded.

Description: DbMpoolFile::get_priority

The DbMpoolFile::get_priority method returns the cache priority.

The DbMpoolFile::get_priority method may be called at any time during the life of the application.

The DbMpoolFile::get_priority method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, and returns 0 on success.

Parameters

priorityp

The DbMpoolFile::get_priority method returns the cache priority in priorityp.

Class

See Also