Hybrid Search Java Api not returning Rank

Elastic Stack Elasticsearch
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1

Hello.
I want to perform hybrid search using java client.
With elasticsarch-java 8.11 environment, this is my query:

SearchResponse<Map> response = esClient.search(s -> s
                .index(index)
                .size(size)
                .query(boolQuery._toQuery())
                .knn(knnQuery)
                .rank(rn->rn.rrf(rrfb->rrfb.rankConstant(20L).windowSize((long) 10))),
                Map.class);

the problem that i have is that response don't contain any field that indicate the rank of the search.
Is this as inteded , so that the rank is the index of the response?

2

Yes the rank is in order of the response. The rank is also specified in the _rank field. Using RRF, both sets of results are merged into a single result set and ranked accordingly.

One thing to note, we don't provide a score for each result but provide a meta rank field in the response only.

See this doc for more information Reciprocal rank fusion | Elasticsearch Guide [8.13] | Elastic

Joe

3

Hi, thank you @joemcelroy, of course using rest Api i see that the response also include the rank,
my problem is when i perform the query with co.elastic.clients library in Java, that the response not include the rank field.
Hope I have explained my problem well,
Thanks,

Tommaso

4

Did you try with a more recent version of the client?
I did not check myself yet but this might have been fixed since then.

5

Hi @dadoonet, no also in new version of java Library i can't see the rank.
last tested 8.13.3

Thanks,
Tommaso.

6

Hello! We seem to be missing the field from the client, if you want you can open an issue on our github repo. Thank you for reporting this!