public void Compact(IDbTableWriter writer)
{
long offset = 0;
foreach (var i in _tree)
{
var length = i.Length;
writer.CopyData(i.Offset, offset, length);
i.Offset = offset;
offset += length;
}
_map = new DataMap <K>(_tree);
}
internal abstract void Write(IDbTableWriter writer, bool crop);