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From Michael McCandless <>
Subject Re: Faceting : what are the limitations of Taxonomy (Separate index and hierarchical facets) and SortedSetDocValuesFacetField ( flat facets and no sidecar index) ?
Date Fri, 11 Nov 2016 22:33:59 GMT
On Fri, Nov 11, 2016 at 5:21 AM, Chitra R <> wrote:

>         i)Hope, when opening SortedSetDocValuesReaderState , we are
> calculating ordinals( this will be used to calculate facet count ) for doc
> values field and this only made the state instance somewhat costly.
>                       Am I right or any other reason behind that?

That's correct.  It adds some latency to an NRT refresh, and some heap
used to hold the ordinal mappings.

>          ii) During indexing, we are providing facet ordinals in each doc
> and I think it will be useful in search side, to calculate facet counts
> only for matching docs.  otherwise, it carries any other benefits?

Well, compared to the taxonomy facets, SSDV facets don't require a
separate index.

But they add latency/heap usage, and they cannot do hierarchical
facets yet (though this could be fixed if someone just built it).

>          iii) Is SortedSetDocValuesReaderState thread-safe (ie) multiple
> threads can call this method concurrently?


Mike McCandless

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