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

# Release 3.1: upgrade requirements

Log file formats and the Btree, Queue, Recno and Hash Access Method database formats changed in the Berkeley DB 3.1 release. (The on-disk Btree/Recno format changed from version 7 to version 8. The on-disk Hash format changed from version 6 to version 7. The on-disk Queue format changed from version 1 to version 2.) Until the underlying databases are upgraded, the DB->open function will return a DB_OLD_VERSION error.

An additional flag, DB_DUPSORT, has been added to the DB->upgrade function for this upgrade. Please review the DB->upgrade documentation for further information.

For further information on upgrading Berkeley DB installations, see Upgrading Berkeley DB installations.

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