#include <db.h>

typedef struct __db_mpoolfile DB_MPOOLFILE;

The memory pool interfaces for the Berkeley DB database environment are methods of the DB_ENV handle. The DB_ENV memory pool methods and the DB_MPOOLFILE class provide general-purpose, page-oriented buffer management of files. Although designed to work with the other DB classes, they are also useful for more general purposes. The memory pools are referred to in this document as simply pools.

Pools may be shared between processes. Pools are usually filled by pages from one or more files. Pages in the pool are replaced in LRU (least-recently-used) order, with each new page replacing the page that has been unused the longest. Pages retrieved from the pool using DB_MPOOLFILE->get are pinned in the pool until they are returned to the control of the buffer pool using the DB_MPOOLFILE->put method.

The DB_MPOOLFILE object is the handle for a file in the memory pool. The handle is not free-threaded. Once the DB_MPOOLFILE->close method is called, the handle may not be accessed again, regardless of that method's return.