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Berkeley DB: Db.set_h_ffactor
Db.set_h_ffactor
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import com.sleepycat.db.*;
public void set_h_ffactor(int h_ffactor)
throws DbException;
Description
Set the desired density within the hash table.
The density is an approximation of the number of keys allowed to
accumulate in any one bucket, determining when the hash table grows or
shrinks. If you know the average sizes of the keys and data in your
data set, setting the fill factor can enhance performance. A reasonable
rule computing fill factor is to set it to the following:
(pagesize - 32) / (average_key_size + average_data_size + 8)
If no value is specified, the fill factor will be selected dynamically as
pages are filled.
The Db.set_h_ffactor interface may be used only to configure Berkeley DB before
the Db.open interface is called.
The Db.set_h_ffactor method throws an exception that encapsulates a non-zero error value on
failure.
Errors
The Db.set_h_ffactor method may fail and throw an exception encapsulating a non-zero error for the following conditions:
- EINVAL
- An invalid flag value or parameter was specified.
Called after Db.open was called.
The Db.set_h_ffactor method may fail and throw an exception for errors specified for other Berkeley DB and C library or system methods.
If a catastrophic error has occurred, the Db.set_h_ffactor method may fail and throw
a DbRunRecoveryException, in which case all subsequent Berkeley DB calls
will fail in the same way.
Class
Db
See Also
Db.associate,
Db.close,
Db.cursor,
Db.del,
Db.fd,
Db.get,
Db.pget,
Db.get_byteswapped,
Db.get_type,
Db.join,
Db.key_range,
Db.open,
Db.put,
Db.remove,
Db.rename,
Db.set_append_recno,
Db.set_bt_minkey,
Db.set_cachesize,
Db.set_errcall,
Db.set_errpfx,
Db.set_feedback,
Db.set_flags,
Db.set_h_ffactor,
Db.set_h_nelem,
Db.set_lorder,
Db.set_pagesize,
Db.set_q_extentsize,
Db.set_re_delim,
Db.set_re_len,
Db.set_re_pad,
Db.set_re_source,
Db.stat,
Db.sync,
Db.truncate,
Db.upgrade,
and
Db.verify.
Copyright Sleepycat Software
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