DbBtreeCompare (Sleepycat Software, Inc. - Berkeley DB Java API)
Keywords: com.sleepycat.db.DbBtreeCompare,DbBtreeCompare interface

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## com.sleepycat.db
Interface DbBtreeCompare

public interface DbBtreeCompare

An interface specifying a comparison function, which imposes a total ordering on the keys in a Btree database.

Method Summary
`int` | `compare(Db db, Dbt dbt1, Dbt dbt2)` The DbBtreeCompare interface is used by the Db.setBtreeCompare method.

Method Detail

### compare

    public int compare(Db db,
                       Dbt dbt1,
                       Dbt dbt2)

  The DbBtreeCompare interface is used by the Db.setBtreeCompare method.

  Parameters:
    `db` - the enclosing database handle.
    `dbt1` - the `Dbt` representing the application supplied key.
    `dbt2` - the `Dbt` representing the current tree's key.
  Returns:
    The bt_compare_fcn function must return an integer value less than, equal to, or greater than zero if the first key parameter is considered to be respectively less than, equal to, or greater than the second key parameter. In addition, the comparison function must cause the keys in the database to be well-ordered. The comparison function must correctly handle any key values used by the application (possibly including zero-length keys). In addition, when Btree key prefix comparison is being performed (see `Db.setBtreePrefix` for more information), the comparison routine may be passed a prefix of any database key. The data and size fields of the `Dbt` are the only fields that may be used for the purposes of this comparison, and no particular alignment of the memory to which by the data field refers may be assumed.

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