Elasticsearch 实现 sql count distinct 的功能（qbit）

前言

• 本文对 Elasticsearch 7.17 适用

count distinct

• 单字段

  "aggs": {
    "card": {
      "cardinality": {
        "field": "type"
      }
    }
  }

• 多字段

  "aggs": {
    "multi_field_cardinality": {
      "cardinality": {
        "script": "doc['type'].value + '#' + doc['color'].value"
      }
    }
  }

  OR

  // 这个写法比上面的写法效率高很多
  {
  "runtime_mappings": {
    "type_and_color": {
      "type": "keyword",
      "script": "emit(doc['type'].value + '#' + doc['color'].value)"
    }
  },
  "aggs": {
    "type_and_color": {
      "cardinality": {
        "field": "type_and_color"
      }
    }
  }
  }

相关阅读

• Elasticsearch Cardinality aggregation 官方文档：https://www.elastic.co/guide/en/elasticsearch/reference/7.17/...
• StackOverflow：Getting cardinality of multiple fields?

本文出自 qbit snap