使用Java API在Spring Boot上的Elasticsearch中对数组元素排序不起作用

Question

I got problem (or lack of knowledge) in sorting documents in elasticsearch. Elasticsearch is local and managed by spring boot. What im trying to do is to, using java API, search documents and sort them. Te docs are looking something like that (little simplified):

{
(...)
"relatedDocuments": [{
    "_id": ObjectId("123123"),
    (...)
    "relationSet": [{
        "type": {
            "name": "Some name",
            "version": NumberLong(1)
        },
        "documentId": "123123",
        "content": {
            "numberToSearch": "U-2016-8"<---element to sort by
        }
    }]
    (...)
}]
(...)
}

As you can see the element to sort by is in object which is in array which is in other object holdet by another array...

Now I'm making some query which seems to work fine but sorting... like sorting never occured... the Java code looks something like:

        BoolQueryBuilder boolQuery = QueryBuilders.boolQuery();
        //some bool query created
        boolQuery.must(query);
        SearchQuery searchQuery = new NativeSearchQueryBuilder().withSort(SortBuilders.fieldSort("relatedDocuments.relationSet.content.numberToSearch").order(SortOrder.ASC).sortMode("min")).withQuery(boolQuery).build();

        return elasticsearchTemplate.queryForList(searchQuery, GenericDocumentIndex.class);

the result is properly searched but not sorted at all...

If I change the fieldSort to something simplier like "relatedDocuments.id" then sorting work...

What is wrong here?

EDIT
for reference resulted rekords are sorted as below:

U-2016-5
U-2016-6
U-2016-7
U-2016-4
U-2016-8
U-2016-9
U-2016-12
U-2016-11
U-2016-10

Answer 1

relationSet seems like a nested field in your schema. 

For Sorting on nested fields, you should refer to the link below

Reference : https://www.elastic.co/guide/en/elasticsearch/guide/current/nested-sorting.html

"sort": [{
        "relatedDocuments.relationSet.content.numberToSearch": {
            "nested_path": "relatedDocuments.relationSet",
            "mode": "min",
            "order": "desc",
            "ignore_unmapped": false
        }
    }],

UPDATE :

You need to explicitly mark relationSet as nested via spring-boot

@Document(indexName = "indexName", type = "inxedType", shards = 1, replicas = 0)
public class RelatedDocuments {
@Field(type= FieldType.Nested)  // <-- mark it as nested
private List<Relation> relationSet;   
}

PS : delete the index and recreate before proceeding

Answer 2

Ok
the issue wasn't in query or document structure but in field value...

it was dash separated so elastic search didnt keep it as whole string but as separated tokens. Solution is to set this field (or add sub field) with index not_analyzed propertie... In java it whould be done by adding annotetion over the field like this or similar:

@Field(
        type = FieldType.String,
        index = FieldIndex.not_analyzed
)