Sheng,
I assume that you're using the Lucene faceting module, so I answer
following that:
(1) A document can be associated with many facet labels, e.g. Tags/lucene
and Author/Shai. The way to extract all facet labels for a particular
document is this:
OrdinalsReader ordinals = new DocValuesOrdinalsReader();
OrdinalsSegmentReader ordsSegment =
ordinals.getReader(indexReader.leaves().get(0)); // we have only one segment
IntsRef scratch = new IntsRef();
ordsSegment.get(0, scratch);
for (int i = 0; i < scratch.length; i++) {
System.out.println(taxoReader.getPath(scratch.ints[i]));
}
Note that OrdinalsSegmentReader works on an AtomicReader. That means that
the doc-id that you pass to it must be relative to the segment. If you have
a global doc-id, you can wrap the DirectoryReader with a
SlowCompositeReaderWrapper, which presents the DirectoryReader as an
AtomicReader.
(2) I'm not quite sure I understand what you mean by "facet cache". Do you
mean the taxonomy index? If so the answer is no. Think of the taxonomy
index is a large global Map<FacetLabel, Integer>, where each facet label is
mapped to an integer, irrespective of the segment it is indexed in. That
map is used to encode the facet information in the *Search Index* more
efficiently.
Therefore the taxonomy index itself doesn't hold all the information that
is needed for faceted search, and you cannot only rebuild it.
Shai
On Wed, Aug 13, 2014 at 8:08 AM, Ralf Heyde <ralf.he...@gmx.de> wrote:
> For 1st: from Solr Level i guess, you could select (only) the document by
> uniqueid. Then you have the facets for that particular document. But this
> results in one additional query/doc.
>
> Gesendet von meinem BlackBerry 10-Smartphone.
> Originalnachricht
> Von: Sheng
> Gesendet: Dienstag, 12. August 2014 23:35
> An: java-user@lucene.apache.org
> Antwort an: java-user@lucene.apache.org
> Betreff: Questions for facets search
>
> I actually have 2 questions:
>
> 1. Is it possible to get the facet label for a particular document? The
> reason we want this is we'd like to allow users to see tags for each hit in
> addition to the taxonomy for his/her search.
>
> 2. Is it possible to re-index the facet cache without reindexing the whole
> lucene cache, since they are separated? We have a dynamic list of faceted
> fields, being able to quickly rebuild the whole facet lucene cache would be
> quite desirable.
>
> Again, I am using lucene 4.7, thanks in advance to your answers!
>
> Sheng
>
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