ElasticSearch | SimpleQueryString | FieldBoosting is not working as expected - elasticsearch

Question

Mapping:
{
"s_q_s" : {
"mappings" : {
"properties" : {
"f1" : {
"type" : "text",
"fields" : {
"keyword" : {
"type" : "keyword",
"ignore_above" : 256
}
}
},
"f2" : {
"type" : "text",
"fields" : {
"keyword" : {
"type" : "keyword",
"ignore_above" : 256
}
}
},
"f3" : {
"type" : "text",
"fields" : {
"keyword" : {
"type" : "keyword",
"ignore_above" : 256
}
}
}
}
}
}
}
Documents:
{
"took" : 1,
"timed_out" : false,
"_shards" : {
"total" : 1,
"successful" : 1,
"skipped" : 0,
"failed" : 0
},
"hits" : {
"total" : {
"value" : 4,
"relation" : "eq"
},
"max_score" : 1.0,
"hits" : [
{
"_index" : "s_q_s",
"_type" : "_doc",
"_id" : "yArwuXQBrACLjhbhLKPa",
"_score" : 1.0,
"_source" : {
"f1" : "major",
"f2" : "general",
"f3" : "ram"
}
},
{
"_index" : "s_q_s",
"_type" : "_doc",
"_id" : "yQrwuXQBrACLjhbhT6OJ",
"_score" : 1.0,
"_source" : {
"f1" : "general",
"f2" : "major",
"f3" : "ram"
}
},
{
"_index" : "s_q_s",
"_type" : "_doc",
"_id" : "ygrxuXQBrACLjhbhi6Op",
"_score" : 1.0,
"_source" : {
"f1" : "general",
"f2" : "major major major",
"f3" : "ram"
}
},
{
"_index" : "s_q_s",
"_type" : "_doc",
"_id" : "ywrxuXQBrACLjhbhuKME",
"_score" : 1.0,
"_source" : {
"f1" : "general",
"f2" : "major major",
"f3" : "ram"
}
}
]
}
}
Query:
GET s_q_s/_search
{
"query": {
"simple_query_string": {
"query": "major",
"fields": ["f1","f2^2"] //<===== f2 is twice important that f1
}
}
}
Result:
"hits" : [
{
"_index" : "s_q_s",
"_type" : "_doc",
"_id" : "yArwuXQBrACLjhbhLKPa",
"_score" : 1.0,
"_source" : {
"f1" : "major",
"f2" : "general",
"f3" : "ram"
}
},
{
"_index" : "s_q_s",
"_type" : "_doc",
"_id" : "yQrwuXQBrACLjhbhT6OJ",
"_score" : 1.0,
"_source" : {
"f1" : "general",
"f2" : "major",
"f3" : "ram"
}
},
{
"_index" : "s_q_s",
"_type" : "_doc",
"_id" : "ygrxuXQBrACLjhbhi6Op",
"_score" : 1.0,
"_source" : {
"f1" : "general",
"f2" : "major major major",
"f3" : "ram"
}
},
{
"_index" : "s_q_s",
"_type" : "_doc",
"_id" : "ywrxuXQBrACLjhbhuKME",
"_score" : 1.0,
"_source" : {
"f1" : "general",
"f2" : "major major",
"f3" : "ram"
}
}
]
Docs Excerpt:
You also can boost relevance scores for matches to particular fields using a caret (^) notation
Question:
Why the document with "major" in f1 in coming on the top rather than once with "major" in f2, when i have defined that f2 is twice as important as f1 while querying ?

Answer 1

According to documentation on boost, individual fields can be boosted automatically — count more towards
the relevance score — at query time, with the boost parameter
Search Query without boost:
{
"query": {
"simple_query_string": {
"fields": [
"f1",
"f2"
],
"query": "major"
}
}
}
Search Result:
"hits": [
{
"_index": "stof_64023501",
"_type": "_doc",
"_id": "1",
"_score": 1.2039728, <-- note this
"_source": {
"f1": "major",
"f2": "general",
"f3": "ram"
}
},
{
"_index": "stof_64023501",
"_type": "_doc",
"_id": "3",
"_score": 0.48608798, <-- note this
"_source": {
"f1": "general",
"f2": "major major major",
"f3": "ram"
}
}
]
Search Query with boost 2:
Matches on the f2 field will have twice the weight as those on the f1 field, but still, the score of f1 field is more than that of f2
You can see in the previous search query, the score of matching f2 field was 0.48608798, now since the boost of 2 is applied, the score has become 0.48608798 * 2 = 0.97217596.
But then also the score of f2 field is less than that of f1 field as 0.97217596 < 1.2039728.
{
"query": {
"simple_query_string": {
"fields": [
"f1",
"f2^2"
],
"query": "major"
}
}
}
Search Result:
"hits": [
{
"_index": "stof_64023501",
"_type": "_doc",
"_id": "1",
"_score": 1.2039728, <-- note this
"_source": {
"f1": "major",
"f2": "general",
"f3": "ram"
}
},
{
"_index": "stof_64023501",
"_type": "_doc",
"_id": "3",
"_score": 0.97217596, <-- note this
"_source": {
"f1": "general",
"f2": "major major major",
"f3": "ram"
}
}
]
Search Query:
Now boosting the f2 field value with parameter 3, you can see significant changes in the score. Therefore, now the result is coming accurately according to your requirement.
{
"query": {
"query_string": {
"fields": [
"f1",
"f2^3"
],
"query": "major"
}
}
}
Search Result:
"hits": [
{
"_index": "stof_64023501",
"_type": "_doc",
"_id": "3",
"_score": 1.4582639,
"_source": {
"f1": "general",
"f2": "major major major",
"f3": "ram"
}
},
{
"_index": "stof_64023501",
"_type": "_doc",
"_id": "4",
"_score": 1.4144535,
"_source": {
"f1": "general",
"f2": "major major",
"f3": "ram"
}
},
{
"_index": "stof_64023501",
"_type": "_doc",
"_id": "2",
"_score": 1.2975104,
"_source": {
"f1": "general",
"f2": "major",
"f3": "ram"
}
},
{
"_index": "stof_64023501",
"_type": "_doc",
"_id": "1",
"_score": 1.2039728,
"_source": {
"f1": "major",
"f2": "general",
"f3": "ram"
}
}
]