Berkeley DB: DbInfo::set_h_hash
Description: Berkeley DB: An embedded database programmatic toolkit.
Keywords: embedded,database,programmatic,toolkit,b+tree,btr ee,hash,hashing,transaction,transactions,locking,logging,access method,access me thods,java,C,C++

# DbInfo::set_h_hash

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    #include <db_cxx.h>

    typedef u_int32_t (*h_hash_fcn)(const void *, u_int32_t);
    void DbInfo::set_h_hash(h_hash_fcn);

# Description

Set a user defined hash method; if no hash method is specified, a default hash method is used. Since no hash method performs equally well on all possible data, the user may find that the built-in hash method performs poorly with a particular data set. User specified hash functions must take a pointer to a byte string and a length as arguments and return a value of type u_int32_t.

If a hash method is specified, hash_open will attempt to determine if the hash method specified is the same as the one with which the database was created, and will fail if it detects that it is not.

# Class

DbInfo

# See Also

DbInfo::set_bt_compare, DbInfo::set_bt_maxkey, DbInfo::set_bt_minkey, DbInfo::set_bt_prefix, DbInfo::set_cachesize, DbInfo::set_compare, DbInfo::set_flags, DbInfo::set_h_ffactor, DbInfo::set_h_hash, DbInfo::set_h_nelem, DbInfo::set_lorder, DbInfo::set_malloc, DbInfo::set_pagesize, DbInfo::set_re_delim, DbInfo::set_re_len, DbInfo::set_re_pad and DbInfo::set_re_source.`