if (file == null)
file = createFileDataInput(positionToSeek);
OnDiskAtom.Serializer atomSerializer = cf.getOnDiskSerializer();
file.seek(positionToSeek);
FileMark mark = file.mark();
// TODO only completely deserialize columns we are interested in
while (file.bytesPastMark(mark) < indexInfo.width)
{
OnDiskAtom column = atomSerializer.deserializeFromSSTable(file, sstable.descriptor.version);
// we check vs the original Set, not the filtered List, for efficiency