/// <summary>
/// Compact the database, and optionally return unused database pages to
/// the underlying filesystem.
/// </summary>
/// <remarks>
/// <para>
/// If <paramref name="txn"/> is non-null, then the operation is
/// performed using that transaction. In this event, large sections of
/// the tree may be locked during the course of the transaction.
/// </para>
/// <para>
/// If <paramref name="txn"/> is null, but the operation occurs in a
/// transactional database, the operation is implicitly transaction
/// protected using multiple transactions. These transactions are
/// periodically committed to avoid locking large sections of the tree.
/// Any deadlocks encountered cause the compaction operation to be
/// retried from the point of the last transaction commit.
/// </para>
/// </remarks>
/// <param name="cdata">Compact configuration parameters</param>
/// <param name="txn">
/// If the operation is part of an application-specified transaction,
/// <paramref name="txn"/> is a Transaction object returned from
/// <see cref="DatabaseEnvironment.BeginTransaction"/>; if
/// the operation is part of a Berkeley DB Concurrent Data Store group,
/// <paramref name="txn"/> is a handle returned from
/// <see cref="DatabaseEnvironment.BeginCDSGroup"/>; otherwise null.
/// </param>
/// <returns>Compact operation statistics</returns>
public CompactData Compact(CompactConfig cdata, Transaction txn)
{
DatabaseEntry end = null;
if (cdata.returnEnd)
{
end = new DatabaseEntry();
}
db.compact(Transaction.getDB_TXN(txn), cdata.start, cdata.stop,
CompactConfig.getDB_COMPACT(cdata), cdata.flags, end);
return(new CompactData(CompactConfig.getDB_COMPACT(cdata), end));
}
