Elasticsearch Prefix query not working on nested documents - elasticsearch

Question

I'm using a prefix query for an elasticsearch query. It works fine when using it on top-level data, but once applied to nested data there are no results returned. The data I try to query looks as follows:
Here the prefix query works fine:
Query:
{ "query": { "prefix" : { "duration": "7"} } }
Result:
{
"took": 25, ... },
"hits": {
"total": 6,
"max_score": 1,
"hits": [
{
"_index": "itemresults",
"_type": "itemresult",
"_id": "ITEM_RESULT_7c8649c2-6cb0-487e-bb3c-c4bf0ad28a90_8bce0a3f-f951-4a01-94b5-b55dea1a2752_7c965241-ad0a-4a83-a400-0be84daab0a9_61",
"_score": 1,
"_source": {
"score": 1,
"studentId": "61",
"timestamp": 1377399320017,
"groupIdentifiers": {},
"assessmentItemId": "7c965241-ad0a-4a83-a400-0be84daab0a9",
"answered": true,
"duration": "7.078",
"metadata": {
"Korrektur": "a",
"Matrize12_13": "MA.1.B.1.d.1",
"Kompetenz": "ZuV",
"Zyklus": "Z2",
"Schwierigkeit": "H",
"Handlungsaspekt": "AuE",
"Fach": "MA",
"Aufgabentyp": "L"
},
"assessmentSessionId": "7c8649c2-6cb0-487e-bb3c-c4bf0ad28a90",
"assessmentId": "8bce0a3f-f951-4a01-94b5-b55dea1a2752"
}
},
Now trying to use the prefix query to apply on the nested structure 'metadata' doesn't return any result:
{ "query": { "prefix" : { "metadata.Fach": "M"} } }
Result:
{
"took": 18,
"timed_out": false,
"_shards": {
"total": 15,
"successful": 15,
"failed": 0
},
"hits": {
"total": 0,
"max_score": null,
"hits": []
}
}
What am I doing wrong? Is it at all possible to apply prefix on nested data?

Answer 1

It does not depends whether is nested or not. It depends on your mapping, if you are analyzing the string at index time or not.
I'm going to put an example:
I've created and index with the following mapping:
curl -XPUT 'http://localhost:9200/test/' -d '
{
"mappings": {
"test" : {
"properties" : {
"text_1" : {
"type" : "string",
"index" : "analyzed"
},
"text_2" : {
"index": "not_analyzed",
"type" : "string"
}
}
}
}
}'
Basically 2 text fields, one analyzed and the other not_analyzed. Now I index the following document:
curl -XPUT 'http://localhost:9200/test/test/1' -d '
{
"text_1" : "Hello world",
"text_2" : "Hello world"
}'
text_1 query
As text_1 is analyzed one of the things that elasticsearch does is to convert the field into lower case. So if I make the following query it doesn't find any document:
curl -XGET 'http://localhost:9200/test/test/_search?pretty=true' -d '
{ "query": { "prefix" : { "text_1": "H"} } }
'
{
"took" : 2,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"failed" : 0
},
"hits" : {
"total" : 0,
"max_score" : null,
"hits" : [ ]
}
}
But if I do the trick and use lower case for making the query:
curl -XGET 'http://localhost:9200/test/test/_search?pretty=true' -d '
{ "query": { "prefix" : { "text_1": "h"} } }
'
{
"took" : 2,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"failed" : 0
},
"hits" : {
"total" : 1,
"max_score" : 1.0,
"hits" : [ {
"_index" : "test",
"_type" : "test",
"_id" : "1",
"_score" : 1.0, "_source" :
{
"text_1" : "Hello world",
"text_2" : "Hello world"
}
} ]
}
}
text_2 query
As text_2 is not analyzed, when I make the original query it matches:
curl -XGET 'http://localhost:9200/test/test/_search?pretty=true' -d '
{ "query": { "prefix" : { "text_2": "H"} } }
'
{
"took" : 1,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"failed" : 0
},
"hits" : {
"total" : 1,
"max_score" : 1.0,
"hits" : [ {
"_index" : "test",
"_type" : "test",
"_id" : "1",
"_score" : 1.0, "_source" :
{
"text_1" : "Hello world",
"text_2" : "Hello world"
}
} ]
}
}