public class IncrementalSelectiveMatching
This class is used by the incremental indexer to do selective matching on a
MultiIndex structure. The basic idea is that you specify a policy to determine
which of the index shards actually get used for each specific query. This is
useful because each shard can be seen as a subset of the documents indexed for
a specific time, hence this class enables one to specify that I want to retrieve
from only the last h hours of documents for example. What selective matching
actually means will be dependent upon the flush policy that is selected, i.e.
is the boundary for a shard based on time, number of documents, etc.