thanks very much for this additional information, Marc!
Am 20.10.23 um 20:30 schrieb Marc D'Mello:
Just following up on Mike's comment:
It used to be that the "doc values" based faceting did not support
arbitrary hierarchy, but I think that was fixed at some point.
Yeah it was fixed a year or two ago, SortedSetDocValuesFacetField supports
hierarchical faceting, I think you just need to enable it in the
FacetsConfig. One thing to keep in mind is even though SSDV faceting
doesn't require a taxonomy index, it still requires a
SortedSetDocValuesReaderState to be maintained, which can be a little bit
expensive to create, but only needs to be done once. This benchmark code
<https://github.com/mikemccand/luceneutil/blob/master/src/main/perf/facets/BenchmarkFacets.java>
serves as a pretty basic example of SSDV/hierarchical SSDV faceting.
On Fri, Oct 20, 2023 at 7:09 AM Michael Wechner <michael.wech...@wyona.com>
wrote:
cool, thank you very much!
Michael
Am 20.10.23 um 15:44 schrieb Michael McCandless:
You can use either the "doc values" implementation for facets
(SortedSetDocValuesFacetField), or the "taxonomy" implementation
(FacetField, in which case, yes, you need to create a TaxonomyWriter).
It used to be that the "doc values" based faceting did not support
arbitrary hierarchy, but I think that was fixed at some point.
Mike McCandless
http://blog.mikemccandless.com
On Fri, Oct 20, 2023 at 9:03 AM Michael Wechner <
michael.wech...@wyona.com>
wrote:
Hi Mike
Thanks for your feedback!
IIUC in order to have the actual advantages of Facets one has to
"connect" it with a TaxonomyWriter
FacetsConfig config = new FacetsConfig();
DirectoryTaxonomyWriter taxoWriter = new
DirectoryTaxonomyWriter(taxoDir);
indexWriter.addDocument(config.build(taxoWriter, doc));
right?
Thanks
Michael
Am 20.10.23 um 12:19 schrieb Michael McCandless:
There are some differences.
StringField is indexed into the inverted index (postings) so you can do
efficient filtering. You can also store in stored fields to retrieve.
FacetField does everything StringField does (filtering, storing
(maybe?)),
but in addition it stores data for faceting. I.e. you can compute
facet
counts or simple aggregations at search time.
FacetField is also hierarchical: you can filter and facet by different
points/levels of your hierarchy.
Mike McCandless
http://blog.mikemccandless.com
On Fri, Oct 20, 2023 at 5:43 AM Michael Wechner <
michael.wech...@wyona.com>
wrote:
Hi
I have found the following simple Facet Example
https://github.com/apache/lucene/blob/main/lucene/demo/src/java/org/apache/lucene/demo/facet/SimpleFacetsExample.java
whereas for a simple categorization of documents I currently use
StringField, e.g.
doc1.add(new StringField("category", "book"));
doc1.add(new StringField("category", "quantum_physics"));
doc1.add(new StringField("category", "Neumann"))
doc1.add(new StringField("category", "Wheeler"))
doc2.add(new StringField("category", "magazine"));
doc2.add(new StringField("category", "astro_physics"));
which works well, but would it be better to use Facets for this, e.g.
doc1.add(new FacetField("media-type", "book"));
doc1.add(new FacetField("topic", "physics", "quantum");
doc1.add(new FacetField("author", "Neumann");
doc1.add(new FacetField("author", "Wheeler");
doc1.add(new FacetField("media-type", "magazine"));
doc1.add(new FacetField("topic", "physics", "astro");
?
IIUC the StringField approach is more general, whereas the FacetField
approach allows to do a more specific categorization / search.
Or do I misunderstand this?
Thanks
Michael
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