Sequence File Index

[Lara Dong]

As now we use the Sequence File to solve the small file problems, but the
Sequence File has no index. What I mean is if I transfer my small file into
a Sequence File, how do I know where is the position to get my file in the
Sequence File? I know the Map File can avoid this problem, but I prefer to
use Sequence File. Just now I use Lucene to build an index to record the
position. Is there a better way?