#include <db.h> int DB_MPOOLFILE->set_priority(DB_MPOOLFILE *mpf, DB_CACHE_PRIORITY priority);
Set the cache priority for pages referenced by the DB_MPOOLFILE 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 DB_MPOOLFILE->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 DB_MPOOLFILE->set_priority()
method using the
DB_MPOOLFILE handle
returned by the
DB->get_mpf()
method.
The DB_MPOOLFILE->set_priority()
method configures a file in the
cache, not only operations performed using the specified
DB_MPOOLFILE handle.
The DB_MPOOLFILE->set_priority()
method may be called at any time
during the life of the application.
The DB_MPOOLFILE->set_priority()
method returns a non-zero error value on failure and 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.