int DB->set_cache_priority(DB *db, DB_CACHE_PRIORITY priority);
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:
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 returns a non-zero error value on failure and 0 on success.
The DB->set_cache_priority method may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions. If a catastrophic error has occurred, the DB->set_cache_priority method may fail and return DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.
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