Class IntervalFacets

  • All Implemented Interfaces:

    public class IntervalFacets
    extends Object
    implements Iterable<IntervalFacets.FacetInterval>
    Computes interval facets for docvalues field (single or multivalued).

    Given a set of intervals for a field and a DocSet, it calculates the number of documents that match each of the intervals provided. The final count for each interval should be exactly the same as the number of results of a range query using the DocSet and the range as filters. This means that the count of facet.query=field:[A TO B] should be the same as the count of f.field.facet.interval.set=[A,B], however, this method will usually be faster in cases where there are a larger number of intervals per field.

    To use this class, create an instance using IntervalFacets(SchemaField, SolrIndexSearcher, DocSet, String[], SolrParams) and then iterate the IntervalFacets.FacetInterval using iterator()

    Intervals Format
    Intervals must begin with either '(' or '[', be followed by the start value, then a comma ',', the end value, and finally ')' or ']'. For example:

    • (1,10) -> will include values greater than 1 and lower than 10
    • [1,10) -> will include values greater or equal to 1 and lower than 10
    • [1,10] -> will include values greater or equal to 1 and lower or equal to 10
    The initial and end values can't be empty, if the interval needs to be unbounded, the special character '*' can be used for both, start and end limit. When using '*', '(' and '[', and ')' and ']' will be treated equal. [*,*] will include all documents with a value in the field

    The interval limits may be strings, there is no need to add quotes, all the text until the comma will be treated as the start limit, and the text after that will be the end limit, for example: [Buenos Aires,New York]. Keep in mind that a string-like comparison will be done to match documents in string intervals (case-sensitive). The comparator can't be changed. Commas, brackets and square brackets can be escaped by using '\' in front of them. Whitespaces before and after the values will be omitted. Start limit can't be grater than the end limit. Equal limits are allowed.

    As with facet.query, the key used to display the result can be set by using local params syntax, for example:

    {!key='First Half'}[0,5)

    To use this class:

     IntervalFacets intervalFacets = new IntervalFacets(schemaField, searcher, docs, intervalStrs, params);
     for (FacetInterval interval : intervalFacets) {
         results.add(interval.getKey(), interval.getCount());