Class FieldsConsumer

  • All Implemented Interfaces:
    Closeable, AutoCloseable
    Direct Known Subclasses:

    public abstract class FieldsConsumer
    extends Object
    implements Closeable
    Abstract API that consumes terms, doc, freq, prox, offset and payloads postings. Concrete implementations of this actually do "something" with the postings (write it into the index in a specific format).
    WARNING: This API is experimental and might change in incompatible ways in the next release.
    • Constructor Detail

      • FieldsConsumer

        protected FieldsConsumer()
        Sole constructor. (For invocation by subclass constructors, typically implicit.)
    • Method Detail

      • write

        public abstract void write​(Fields fields)
                            throws IOException
        Write all fields, terms and postings. This the "pull" API, allowing you to iterate more than once over the postings, somewhat analogous to using a DOM API to traverse an XML tree.


        • You must compute index statistics, including each Term's docFreq and totalTermFreq, as well as the summary sumTotalTermFreq, sumTotalDocFreq and docCount.
        • You must skip terms that have no docs and fields that have no terms, even though the provided Fields API will expose them; this typically requires lazily writing the field or term until you've actually seen the first term or document.
        • The provided Fields instance is limited: you cannot call any methods that return statistics/counts; you cannot pass a non-null live docs when pulling docs/positions enums.
      • merge

        public void merge​(MergeState mergeState)
                   throws IOException
        Merges in the fields from the readers in mergeState. The default implementation skips and maps around deleted documents, and calls write(Fields). Implementations can override this method for more sophisticated merging (bulk-byte copying, etc).