### Berkeley DB Reference Guide: Upgrading Berkeley DB Applications |

### Release 3.2: DB callback functions, app_private field

In the Berkeley DB 3.2 release, four application callback functions (the callback functions set by DB->set_bt_compare, DB->set_bt_prefix, DB->set_dup_compare and DB->set_h_hash) were modified to take a reference to a DB object as their first argument. This change allows the Berkeley DB Java API to reasonably support these interfaces. There is currently no need for the callback functions to do anything with this additional argument.

C and C++ applications that specify their own Btree key comparison, Btree prefix comparison, duplicate data item comparison or Hash functions should modify these functions to take a reference to a DB structure as their first argument. No further change is required.

The app_private field of the DBT structure (accessible only from the Berkeley DB C API) has been removed in the 3.2 release. It was replaced with app_private fields in the DB_ENV and DB handles. Applications using this field will have to convert to using one of the replacement fields.

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