Class BlockTreeTermsReader

  • All Implemented Interfaces:
    Closeable, AutoCloseable, Iterable<String>

    public class BlockTreeTermsReader
    extends FieldsProducer
    A block-based terms index and dictionary that assigns terms to variable length blocks according to how they share prefixes. The terms index is a prefix trie whose leaves are term blocks. The advantage of this approach is that seekExact is often able to determine a term cannot exist without doing any IO, and intersection with Automata is very fast. Note that this terms dictionary has it's own fixed terms index (ie, it does not support a pluggable terms index implementation).

    NOTE: this terms dictionary does not support index divisor when opening an IndexReader. Instead, you can change the min/maxItemsPerBlock during indexing.

    The data structure used by this implementation is very similar to a burst trie (http://citeseer.ist.psu.edu/viewdoc/summary?doi=10.1.1.18.3499), but with added logic to break up too-large blocks of all terms sharing a given prefix into smaller ones.

    Use CheckIndex with the -verbose option to see summary statistics on the blocks in the dictionary. See BlockTreeTermsWriter.