Hey guys,
While doing some tests related to searching across multiple fields I
stumbled upon a behavior with multi field query_string query that seems to
contradict what is stated in the official documentation. Below is what the
documentation says on this matter:
"The idea of running the query_string query against multiple fields is by
internally creating several queries for the same query string, each with
default_field that match the fields provided."
Elasticsearch Platform — Find real-time answers at scale | Elastic
So, given the information above, I expected that the following multi field
query:
curl -XGET 'localhost:9200/testgroupquery/_search?pretty' -d '{
"query": {
"query_string": {
"fields": [
"title",
"address"
],
"auto_generate_phrase_queries": true,
"boost": 1.0,
"default_operator": "and",
"use_dis_max" : true,
"query": "hotel praha"
}
}
}'
Would translate into a dis_max query like this:
curl -XGET 'localhost:9200/testgroupquery/_search?pretty' -d '{
"query": {
"dis_max" : {
"tie_breaker" : 0.0,
"queries" : [
{
"query_string": {
"default_field": "title",
"auto_generate_phrase_queries": true,
"boost": 1.0,
"default_operator": "and",
"query": "hotel praha"
}
},
{
"query_string": {
"default_field": "address",
"auto_generate_phrase_queries": true,
"boost": 1.0,
"default_operator": "and",
"query": "hotel praha"
}
}
]
}
}
}'
But apparently it doesn't. I first noticed this because the resultset
returned is different between these two queries: while the multi field
query_string query matches all documents containing both "hotel" and
"praha" in the title and/or address fields (including cross matching
between the fields - e.g. "hotel" in title and "praha" in address), the
dis_max query above returns just documents that contain both terms "hotel"
and "praha" in the same field (either title or address).
Looking at the final query for these two distinct requests using the
Validate API, I can see that the output is quite different indeed:
multi field query_string query
curl -XGET
'localhost:9200/testgroupquery/_validate/query?pretty&explain=true' -d '{
"query_string": {
"fields": [
"title",
"address"
],
"auto_generate_phrase_queries": true,
"boost": 1.0,
"default_operator": "and",
"use_dis_max" : true,
"query": "hotel praha"
}
}'
{
"valid" : true,
"_shards" : {
"total" : 1,
"successful" : 1,
"failed" : 0
},
"explanations" : [ {
"index" : "testgroupquery",
"valid" : true,
"explanation" : "+(title:hotel | address:hotel) +(title:praha |
address:praha)"
} ]
}
dis_max query
*
*
curl -XGET
'localhost:9200/testgroupquery/_validate/query?pretty&explain=true' -d '{
"dis_max" : {
"tie_breaker" : 0.0,
"queries" : [
{
"query_string": {
"default_field": "title",
"auto_generate_phrase_queries": true,
"boost": 1.0,
"default_operator": "and",
"query": "hotel praha"
}
},
{
"query_string": {
"default_field": "address",
"auto_generate_phrase_queries": true,
"boost": 1.0,
"default_operator": "and",
"query": "hotel praha"
}
}
]
}
}'
{
"valid" : true,
"_shards" : {
"total" : 1,
"successful" : 1,
"failed" : 0
},
"explanations" : [ {
"index" : "testgroupquery",
"valid" : true,
"explanation" : "((+title:hotel +title:praha) | (+address:hotel
+address:praha))"
} ]
}
The reason I'm pointing out this difference is that I've been trying to
configure my application to work in precisely the way the multi field
query_string query works, allowing users to search for multiple terms
allowing matches across multiple fields. So that's exactly the behavior I
want, but it seems to contradict what is in the documentation, so I want to
make sure this matching across multiple fields is an expected behavior and
not some anomaly that will be corrected at some point.
In case it helps, the attached document contains all the requests to create
the index and populate it with sample data, along with my query
requests+response for each of the tests I did.
Thank you in advance for your help.
Best,
Leo
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