[jira] [Comment Edited] (LUCENE-9444) Need an API to easily fetch facet labels for a field in a document

["Ankur (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-9444?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17171215#comment-17171215 ] 

Ankur edited comment on LUCENE-9444 at 8/5/20, 1:38 AM:
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Thanks for your response [~mikemccand]

Yes, having _dim_ as additional parameter makes sense.

Regarding _*BinaryDocValues*_ iterator, initially I was thinking of providing a concrete implementation - *_TaxonomyFacetsLabels_* of abstract class *_TaxonomyFacets_* and add a constructor that accepts a *_LeafReaderContext_* which will then be used to instantiate and reuse the BinaryDocValues iterator between multiple calls to *getLabels(docId, dim).* That way a caller does not need to know if a _*BinaryDocValues*_ field existed at all. The downside is that caller will need to create a new instance of *_TaxonomyFacetsLabels_* for each different *_LeafReaderContext._*

But thinking more, I feel its simpler to pass BinaryDocValues iterator as a 3rd argument to *getLabels().* In order to take care of hierarchical fields, I think it makes sense to return FacetLabel[] instead of String[].

The proposed API signature would look like this

{{public static FacetLabel[] getLabels(int docId, String dim, BinaryDocValues)}}

 


was (Author: goankur):
Thanks for your response [~mikemccand]

Yes, having _dim_ as additional parameter makes sense.

Regarding _*BinaryDocValues*_ iterator, initially I was thinking of providing a concrete implementation - *_TaxonomyFacetsLabels_* of abstract class *_TaxonomyFacets_* and add a constructor that accepts a *_LeafReaderContext_* which will then be used to instantiate and reuse the BinaryDocValues iterator between multiple calls to *getLabels(docId, dim).* That way a caller does not need to know if a _*BinaryDocValues*_ field existed at all. The downside is that caller will need to create a new instance of *_TaxonomyFacetsLabels_* for each different *_LeafReaderContext._*

But thinking more, I feel its simpler to pass BinaryDocValues iterator as a 3rd argument to *getLabels().*

In order to take care of hierarchical fields, I think it makes sense to return FacetLabel[] instead of String[].

One last thing, should we make the API _*static*_ ?

The proposed API signature would look like this

{{public static FacetLabel[] getLabels(int docId, String dim, BinaryDocValues)}}

 

> Need an API to easily fetch facet labels for a field in a document
> ------------------------------------------------------------------
>
>                 Key: LUCENE-9444
>                 URL: https://issues.apache.org/jira/browse/LUCENE-9444
>             Project: Lucene - Core
>          Issue Type: Improvement
>          Components: modules/facet
>    Affects Versions: 8.6
>            Reporter: Ankur
>            Priority: Major
>
> A facet field may be included in the list of fields whose values are to be returned for each hit.
> In order to get the facet labels for each hit we need to
>  # Create an instance of _DocValuesOrdinalsReader_ and invoke _getReader(LeafReaderContext context)_ method to obtain an instance of _OrdinalsSegmentReader()_
>  # _OrdinalsSegmentReader.get(int docID, IntsRef ordinals)_ method is then used to fetch and decode the binary payload in the document's BinaryDocValues field. This provides the ordinals that refer to facet labels in the taxonomy.**
>  # Lastly TaxonomyReader.getPath(ord) is used to fetch the labels to be returned.
>  
> Ideally there should be a simple API - *String[] getLabels(docId)* that hides all the above details and gives us the string labels. This can be part of *TaxonomyFacets* but that's just one idea.
> I am opening this issue to get community feedback and suggestions.
>  



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