DbMpoolFile::set_priority()
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## DbMpoolFile::set_priority()

    #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.

### 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.

### Class

DbEnv, DbMpoolFile

### See Also

Memory Pools and Related Methods

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