elasticsearch篇：DSL查询语法

Elasticsearch的查询语言(Query DSL)是一种JSON形式的语法，用于构建查询。以下是一些基本查询的例子：

1. 全文搜索查询(Full text search):

GET /_search
{
  "query": {
    "match": {
      "message": "elasticsearch"
    }
  }
}

2. 多字段匹配查询(Multi-field match query):

GET /_search
{
  "query": {
    "multi_match": {
      "query":    "elasticsearch",
      "fields":   ["title^2", "*_name"]
    }
  }
}

3. 范围查询(Range query):

GET /_search
{
  "query": {
    "range": {
      "age": {
        "gte":  20,
        "lt":   30
      }
    }
  }
}

4. 过滤器查询(Filter query):

GET /_search
{
  "query": {
    "bool": {
      "must": {
        "match": {
          "message": "elasticsearch"
        }
      },
      "filter": {
        "range": {
          "timestamp": {
            "gte": "2014-01-01",
            "lt":  "2015-01-01"
          }
        }
      }
    }
  }
}

5. 精确匹配查询(Term query):

GET /_search
{
  "query": {
    "term": {
      "category": "electronics"
    }
  }
}

6. 布尔查询(Boolean query):

GET /_search
{
  "query": {
    "bool": {
      "must":     { "match": { "title": "elasticsearch" }},
      "must_not": { "match": { "title": "kibana" }},
      "filter":   { "range": { "price": { "lte": 100 }}}
    }
  }
}

7. 地理坐标查询(Geo-distance query):

GET /_search
{
  "query": {
    "geo_distance": {
      "distance": "20km",
      "pin.location": {
        "lat":  40,
        "lon": -70
      }
    }
  }
}

8. 高亮查询(Highlight query):

GET /_search
{
  "query": {
    "match": {
      "message": "elasticsearch"
    }
  },
  "highlight": {
    "fields": {
      "message": {}
    }
  }
}

这些查询可以根据需求进行组合和嵌套，以构建更复杂的搜索逻辑。