How to create sub-bucket aggregation on the basis of hierarchy field value (part of the field)-CodePudding

Assuming that we have a documents that has a hierarchy field like this:

POST subbuckets/_doc
{
  "hierarchy": "this/is/some/hierarchy"
}

POST subbuckets/_doc
{
  "hierarchy": "this/is/some/hierarchy2"
}

POST subbuckets/_doc
{
  "hierarchy": "this/is/another/hierarchy1"
}

I would like to count number of documents that belongs to each hierarchy level I.e.

"this" hierarchy level has 3 documents
"this/is" hierarchy level has 3 documents
"this/is/some" hierarchy level has 2 documents
"this/is/another" hierarchy level has 1 document
"this/is/another/hierarchy1" hierarchy level has 1 document
"this/is/some/hierarchy" hierarchy level has 1 document
"this/is/some/hierarchy2" hierarchy level has 1 document

CodePudding user response：

We can not applied analyzer on keyword so to resolved this issue we have define field as text type and enable aggregation on text field and set "fielddata": true. Please check below configuration.

Index Mapping:

PUT index5
{
  "settings": {
    "analysis": {
      "analyzer": {
        "path-analyzer": {
          "tokenizer": "path-tokenizer"
        }
      },
      "tokenizer": {
        "path-tokenizer": {
          "type": "path_hierarchy",
          "delimiter": "/"
        }
      }
    }
  },
  "mappings": {
    "properties": {
      "hierarchy": {
        "type": "text",
        "analyzer": "path-analyzer",
        "search_analyzer": "keyword",
        "fielddata": true
      }
    }
  }
}

Index Documents:

POST index5/_doc
{
  "hierarchy": "this/is/some/hierarchy"
}

POST index5/_doc
{
  "hierarchy": "this/is/some/hierarchy2"
}

POST index5/_doc
{
  "hierarchy": "this/is/another/hierarchy1"
}

Query:

POST index5/_search
{
  "aggs": {
    "path": {
      "terms": {
        "field": "hierarchy"
      }
    }
  },
  "size": 0
}

Response:

{
 "aggregations" : {
    "path" : {
      "doc_count_error_upper_bound" : 0,
      "sum_other_doc_count" : 0,
      "buckets" : [
        {
          "key" : "this",
          "doc_count" : 3
        },
        {
          "key" : "this/is",
          "doc_count" : 3
        },
        {
          "key" : "this/is/some",
          "doc_count" : 2
        },
        {
          "key" : "this/is/another",
          "doc_count" : 1
        },
        {
          "key" : "this/is/another/hierarchy1",
          "doc_count" : 1
        },
        {
          "key" : "this/is/some/hierarchy",
          "doc_count" : 1
        },
        {
          "key" : "this/is/some/hierarchy2",
          "doc_count" : 1
        }
      ]
    }
  }
}