elasticsearch filter on nested array - elasticsearch

Question

lets say records have city field as an array of city names.
records ex:
record 1:
{
cities : [
{name: city1},
{name : city2},
{name : city3}
]
}
record 2:
{
cities : [
{name: city2},
{name : city3},
{name : city4}
]
}
record 3:
{
cities : [
{name: city3},
{name : city4},
{name : city5}
]
}
requirement:
My filter criteria is to fetch the records matches with city1 or city2 or city3 but since the record 1 matches all 3 it should come first and record 2 matches 2 so it should come 2nd and record 3 matches only one so it should come last.

Answer 1

You don't have to use the nested data-type as you don't have the nested properties or complex object, its very simple and easy to achieve.
Working example
Index mapping
{
"mappings": {
"properties": {
"cities": {
"type": "text"
}
}
}
}
Index sample docs
{
"cities": [
"tel-aviv", "bangalore", "sf"
]
}
{
"cities": [
"tel-aviv"
]
}
{
"cities": [
"sf"
]
}
Search query
{
"query": {
"bool": {
"should": [
{
"match": {
"cities": "tel-aviv"
}
},
{
"match": {
"cities": "bangalore"
}
},
{
"match": {
"cities": "sf"
}
}
]
}
}
}
And search result with proper expected result and score
"hits": [
{
"_index": "cities",
"_type": "_doc",
"_id": "1",
"_score": 1.850198,
"_source": {
"cities": [
"tel-aviv",
"bangalore",
"sf"
]
}
},
{
"_index": "cities",
"_type": "_doc",
"_id": "2",
"_score": 0.9983525,
"_source": {
"cities": [
"tel-aviv"
]
}
},
{
"_index": "cities",
"_type": "_doc",
"_id": "3",
"_score": 0.6133945,
"_source": {
"cities": [
"sf"
]
}
}
]

Answer 2

Adding another answer with nested bool queries:
Index Mapping:
{
"mappings": {
"properties":{
"Cities": {
"type": "nested",
"dynamic": "true"
}
}}
}
Index Data:
{
"Cities": [
{
"id": 1,
"city": "Bangalore"
},
{
"id": 2,
"city": "Hyderabad"
},
{
"id": 3,
"city": "Delhi"
}
]
}
{
"Cities": [
{
"id": 1,
"city": "Bangalore"
},
{
"id": 2,
"city": "abc"
},
{
"id": 3,
"city": "Def"
}
]
}
Search Query:
{
"query": {
"bool": {
"should": [
{
"nested": {
"path": "Cities",
"query": {
"bool": {
"must": [
{
"match": {
"Cities.city": "Bangalore"
}
}
]
}
}
}
},
{
"nested": {
"path": "Cities",
"query": {
"bool": {
"must": [
{
"match": {
"Cities.city": "Hyderabad"
}
}
]
}
}
}
}
]
}
}
}
Search Result:
"hits": [
{
"_index": "nested-63806067",
"_type": "_doc",
"_id": "1",
"_score": 3.297317, <-- note this
"_source": {
"Cities": [
{
"id": 1,
"city": "Bangalore"
},
{
"id": 2,
"city": "Hyderabad"
},
{
"id": 3,
"city": "Delhi"
}
]
}
},
{
"_index": "nested-63806067",
"_type": "_doc",
"_id": "2",
"_score": 1.6486585, <-- note this
"_source": {
"Cities": [
{
"id": 1,
"city": "Bangalore"
},
{
"id": 2,
"city": "abc"
},
{
"id": 3,
"city": "Def"
}
]
}
}
]