#include <db_cxx.h>

int
Db::set_cache_priority(DB_CACHE_PRIORITY priority);

Description

Set the cache priority for pages from the specified database. 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 Db::set_cache_priority interface is only advisory, and does not guarantee pages will be treated in a specific way.

The priority argument 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.

The Db::set_cache_priority method configures a database, not only operations performed using the specified Db handle.

The Db::set_cache_priority interface may be called at any time during the life of the application.

The Db::set_cache_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.

Errors

The Db::set_cache_priority method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods. If a catastrophic error has occurred, the Db::set_cache_priority method may fail and either return DB_RUNRECOVERY or throw a DbRunRecoveryException, in which case all subsequent Berkeley DB calls will fail in the same way.

Class

See Also