composite 多字段聚合按照count值降序返回

To answer your first question, no, there isn't a way to order by doc count with the composite aggregation. Ordering would require passing over the entire dataset first and keeping a record of how many docs each term has, which would require memory equivalent to the number of terms.

That's opposite of what the composite agg is made for: it's designed as a memory-friendly way to paginate over aggregations. Part of the tradeoff is that you lose things like ordering by doc count, since that isn't known until after all the docs have been collected.

PUT test_index

{

  "settings": {

    "refresh_interval": "1s",

    "number_of_shards": "1",

    "number_of_replicas": "0"

  },

  "mappings": {

    "properties": {

      "keyword": {

        "type": "keyword"

      },

      "number": {

        "type": "integer"

      }

    }

  }

}

POST test_index/_doc

{

    "keyword": ["foo", "bar"],

    "number": [23, 65, 76]

}

{

  "size": 0,

  "aggs": {

    "my_buckets": {

      "composite": {

        "sources": [

          {

            "product": {

              "terms": {

                "field": "keyword",

                "order": "desc"

              }

            }

          }

        ]

      }

    }

  }

}

POST test_index/_search

{

  "size": 0,

  "aggs": {

    "my_buckets": {

      "composite": {

        "sources": [

          {

            "product": {

              "terms": {

                "field": "keyword",

                "order": "desc"

              }

            }

          }

        ]

      }

    }

  }

}

{

  "took" : 1,

  "timed_out" : false,

  "_shards" : {

    "total" : 1,

    "successful" : 1,

    "skipped" : 0,

    "failed" : 0

  },

  "hits" : {

    "total" : {

      "value" : 15,

      "relation" : "eq"

    },

    "max_score" : null,

    "hits" : [ ]

  },

  "aggregations" : {

    "my_buckets" : {

      "after_key" : {

        "product" : "bar"

      },

      "buckets" : [

        {

          "key" : {

            "product" : "foo"

          },

          "doc_count" : 11

        },

        {

          "key" : {

            "product" : "bar"

          },

          "doc_count" : 8

        }

      ]

    }

  }

}

POST test_index/_search

{

  "size": 0,

  "aggs": {

    "my_buckets": {

      "composite": {

        "sources": [

          {

            "product": {

              "terms": {

                "field": "keyword"

              }

            }

          }

        ]

      }

    }

  }

}

{

  "took" : 1,

  "timed_out" : false,

  "_shards" : {

    "total" : 1,

    "successful" : 1,

    "skipped" : 0,

    "failed" : 0

  },

  "hits" : {

    "total" : {

      "value" : 15,

      "relation" : "eq"

    },

    "max_score" : null,

    "hits" : [ ]

  },

  "aggregations" : {

    "my_buckets" : {

      "after_key" : {

        "product" : "foo"

      },

      "buckets" : [

        {

          "key" : {

            "product" : "bar"

          },

          "doc_count" : 8

        },

        {

          "key" : {

            "product" : "foo"

          },

          "doc_count" : 11

        }

      ]

    }

  }

}