Why am I writing this shit, beacause the official documentation really really sucks, though you might find this article about es search api and query dsl sucks more.

Elasticsearch可以通過search api提供對文檔的精細檢索。Elasticsearch的search api對文檔的精細檢索主要靠Elasticsearch的DSL檢索語言實現(xiàn)，它通過自身的query參數(shù)指定具體的DSL查詢語句。

• search api
  • 具體語法見https://www.elastic.co/guide/en/elasticsearch/reference/current/search-search.html#search-multi-index-type。
  • 主要關(guān)注帶request body的api調(diào)用形式，因為DSL必須在這種形式下才可以使用。

    curl -XGET 'http://host:port/index/doc/_search' -d ' {   # request body
        ... 
        "query": {DSL_QUERY_CLAUSE}                          # query 參數(shù)
        ...
    }'

• DSL語法

    DSL_QUERY_CLAUSE: 
    {
        QUERY_NAME: 
        {
            FIELD_NAME: 
            {
                ARGUMENT: VALUE,
                ARGUMENT: VALUE
               ...
            }
        }
    }

• DSL 上下文

  • query context(按匹配程度篩選結(jié)果)
    • A query clause used in query context answers the question “How well does this document match this query clause?”
  • filter context(類似精確匹配)
    • In filter context, a query clause answers the question “Does this document match this query clause?”

• Query clause 類型

  • leave clause
  • compound clause
    • wrap other leaf or compound queries and used to combine multiple queries in a logical fashion(quote from official documentation).

• compound queries

  • 比較重要，因為需要使用復(fù)合查詢的場景可能比較多
  • 通過復(fù)合查詢，可以指定子查詢是query context還是filter context
  • https://www.elastic.co/guide/en/elasticsearch/reference/current/compound-queries.html
  • eg
    • bool query https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-bool-query.html