Is it possible to set the TYPE parameter using simple query string query in Elastic Search - elasticsearch

Question

When using a query string query in ES and matching multiple fields, I can set a TYPE paramter to configure how ES combines/scores when matching on multiple fields.
e.g. I want to match two fields in my index, and combine scores from both fields
GET /_search
{
"query": {
"query_string" : {
"query" : "test",
"fields": ["titel", "content"],
"type": "most_fields"
}
}
}
The parameter seems to be missing using the simple query string. What is the default mode for simple query string? How are scores chosen/combined? Is it possible to set type.

Answer 1

Simple query string doesn't have a type parameter. It does a sum of score from each field.
Consider below index and let's see how different queries calculate score using explanation api
Mapping:
PUT testindex6
{
"mappings": {
"properties": {
"title":{
"type": "text"
},
"description":{
"type": "text"
}
}
}
}
Data:
POST testindex6/_doc
{
"title": "dog",
"description":"dog is brown"
}
1. Query_string best_fields(default)
Finds documents which match any field, but uses the _score from the
best field
GET testindex6/_search?explain=true
{
"query": {
"query_string": {
"default_field": "*",
"query": "dog brown",
"type":"best_fields"
}
}
}
Result:
"_explanation" : {
"value" : 0.5753642,
"description" : "max of:",
"details" : [
{
"value" : 0.5753642,
"description" : "sum of:",
},
{
"value" : 0.2876821,
"description" : "sum of:",
}
]
}
Best_fields takes max score from matched fields
2. Query_string most_fields
Does sum of scores from matched fields
GET testindex6/_search?explain=true
{
"query": {
"query_string": {
"default_field": "*",
"query": "dog brown",
"type":"most_fields"
}
}
}
Result
"_explanation" : {
"value" : 0.8630463,
"description" : "sum of:",
"details" : [
{
"value" : 0.5753642,
"description" : "sum of:"
....
},
{
"value" : 0.2876821,
"description" : "sum of:"
....
}
]
}
}
3. Simple_Query_String
Query
GET testindex6/_search?explain=true
{
"query": {
"simple_query_string": {
"query": "dog brown",
"fields": ["*"]
}
}
}
Result:
"_explanation" : {
"value" : 0.8630463,
"description" : "sum of:",
"details" : [
{
"value" : 0.5753642,
"description" : "sum of:",
},
{
"value" : 0.2876821,
"description" : "sum of:"
}
]
}
}
So you can see score is same in most_fields and simple_query_string(both do a sum of). But there is difference in them. Consider below index
I have created a field title with type text and subfield shingles with shingles analyzer.
PUT index_2
{
"settings": {
"analysis": {
"analyzer": {
"analyzer_shingle": {
"tokenizer": "standard",
"filter": [
"lowercase",
"shingle"
]
}
}
}
},
"mappings": {
"properties": {
"title": {
"type": "text",
"fields": {
"shingles": {
"search_analyzer": "analyzer_shingle",
"analyzer": "analyzer_shingle",
"type": "text"
}
}
}
}
}
}
Data:
POST index_2/_doc
{
"title":"the brown fox"
}
1. Most_fields
Query:
GET index_2/_search?explain=true
{
"query": {
"query_string": {
"query": "brown fox",
"fields": ["*"],
"type":"most_fields"
}
}
}
Result:
"_explanation" : {
"value" : 1.3650365,
"description" : "sum of:",
"details" : [
{
"value" : 0.7896724,
"description" : "sum of:",
},
{
"value" : 0.5753642,
"description" : "sum of:",
}
]
}
2. Simple_Query_string
Query
GET index_2/_search?explain=true
{
"query": {
"simple_query_string": {
"query": "brown fox",
"fields": ["*"]
}
}
}
Result:
"_explanation" : {
"value" : 1.2632996,
"description" : "sum of:",
"details" : [
{
"value" : 0.6316498,
"description" : "sum of:",
},
{
"value" : 0.6316498,
"description" : "sum of:"
}
]
}
}
If you will see the score is different in most_fields and simple_query_string even though both do sum of scores.
The reason is most_fields uses analyzer of field while querying ,remember titles(standard) and titles shingles(analyzer_shingle) have different analyzer while simple_query_string use default analyzer of the index(standard) for all fields.
If we will query most_fields and force it to use standard analyzer you will score is same
Query:
GET index_2/_search?explain=true
{
"query": {
"query_string": {
"query": "brown fox",
"fields": ["*"],
"type":"most_fields",
"analyzer": "standard"-->instead of field analyzer respectively use standard for all
}
}
}
Result:
"_explanation" : {
"value" : 1.2632996,
"description" : "sum of:"
"details" : [
{
"value" : 0.6879354,
"description" : "sum of:"
},
{
"value" : 0.5753642,
"description" : "sum of:"
}
]
}
simple_query_string I think is for simple scenarios, if you are using different analyzers for different field use simple_query_string or bool- match queries