#include <db_cxx.h> int DbMpoolFile::set_priority(DB_CACHE_PRIORITY priority);
Set the cache priority for pages referenced by the DbMpoolFile handle.
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 cache.
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 the
Db::get_mpf()
method.
The DbMpoolFile::set_priority()
method configures a file in the
cache, 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.
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.