Elasticsearch aggregations: how to get bucket with 'other' results of terms aggregation? - elasticsearch

Question

I use aggregation to collect data from nested field and stuck a little
Example of document:
{
...
rectangle: {
attributes: [
{_id: 'some_id', ...}
]
}
ES allows group data by rectangle.attributes._id, but is there any way to get some 'other' bucket to put there documents that were not added to any of groups? Or maybe there is a way to create query to create bucket for documents by {"rectangle.attributes._id": {$ne: "{currentDoc}.rectangle.attributes._id"}}
I think bucket would be perfect because i need to do further aggregations with 'other' docs.
Or maybe there's some cool workaround
I use query like this for aggregation
"aggs": {
"attributes": {
"nested": {
"path": "rectangle.attributes"
},
"aggs": {
"attributesCount": {
"cardinality": {
"field": "rectangle.attributes._id.keyword"
}
},
"entries": {
"terms": {
"field": "rectangle.attributes._id.keyword"
}
}
}
}
}
And get this result
"buckets" : [
{
"key" : "some_parent_id",
"doc_count" : 27616,
"attributes" : {
"doc_count" : 45,
"entries" : {
"doc_count_error_upper_bound" : 0,
"sum_other_doc_count" : 0,
"buckets" : [
{
"key" : "some_id",
"doc_count" : 45,
"attributeOptionsCount" : {
"value" : 2
}
}
]
}
}
}
]
result like this would be perfect:
"buckets" : [
{
"key" : "some_parent_id",
"doc_count" : 1000,
"attributes" : {
"doc_count" : 145,
"entries" : {
"doc_count_error_upper_bound" : 0,
"sum_other_doc_count" : 0,
"buckets" : [
{
"key" : "some_id",
"doc_count" : 45
},
{
"key" : "other",
"doc_count" : 100
}
]
}
}
}
]

Answer 1

You can make use of missing value parameter. Update aggregation as below:
"aggs": {
"attributes": {
"nested": {
"path": "rectangle.attributes"
},
"aggs": {
"attributesCount": {
"cardinality": {
"field": "rectangle.attributes._id.keyword"
}
},
"entries": {
"terms": {
"field": "rectangle.attributes._id.keyword",
"missing": "other"
}
}
}
}
}