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Reverse nested aggregations
You can aggregate values from nested documents to their parent; this aggregation is called reverse_nested. You can use reverse_nested to aggregate a field from the parent document after grouping by the field from the nested object. The reverse_nested aggregation “joins back” the root page and gets the load_time for each for your variations.
The reverse_nested aggregation is a sub-aggregation inside a nested aggregation. It accepts a single option named path. This option defines how many steps backwards in the document hierarchy OpenSearch takes to calculate the aggregations.
GET logs/_search
{
"query": {
"match": { "response": "200" }
},
"aggs": {
"pages": {
"nested": {
"path": "pages"
},
"aggs": {
"top_pages_per_load_time": {
"terms": {
"field": "pages.load_time"
},
"aggs": {
"comment_to_logs": {
"reverse_nested": {},
"aggs": {
"min_load_time": {
"min": {
"field": "pages.load_time"
}
}
}
}
}
}
}
}
}
}
Example response
...
"aggregations" : {
"pages" : {
"doc_count" : 2,
"top_pages_per_load_time" : {
"doc_count_error_upper_bound" : 0,
"sum_other_doc_count" : 0,
"buckets" : [
{
"key" : 200.0,
"doc_count" : 1,
"comment_to_logs" : {
"doc_count" : 1,
"min_load_time" : {
"value" : null
}
}
},
{
"key" : 500.0,
"doc_count" : 1,
"comment_to_logs" : {
"doc_count" : 1,
"min_load_time" : {
"value" : null
}
}
}
]
}
}
}
}
The response shows the logs index has one page with a load_time of 200 and one with a load_time of 500.