Elasticsearch Query DSL之Compound queries（复合查询）

本章开始将介绍Elasticsearch DSL查询语法的复合查询。

复合查询将其他复合查询或叶子查询进行包装，组合它们的结果和分数，以此改变它们的行为，或从查询字句切换到过滤上下文模式。

主要的复合查询包括如下：

• constant_score query
• bool query
• dis_max query
• function_score query
• boosting query

1、constant_score query

常量(score)评分查询，该复合查询将忽略文档本身的匹配相关性评分，而是统一返回请求参数的boost。

举例说明：(JAVA示例)

public static void testConstantScoreQuery() {
		RestHighLevelClient client = EsClient.getClient();
		try { SearchRequest searchRequest = new SearchRequest(); searchRequest.indices("twitter"); SearchSourceBuilder sourceBuilder = new SearchSourceBuilder(); sourceBuilder.query( QueryBuilders.constantScoreQuery(QueryBuilders.wildcardQuery("user", "ding*")) .boost(1.5f) ); searchRequest.source(sourceBuilder); SearchResponse result = client.search(searchRequest, RequestOptions.DEFAULT); System.out.println(result);
		} catch (Throwable e) { e.printStackTrace();
		} finally { EsClient.close(client);
		}
	}

  

 

  
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返回的结果为：为了对比，左边的结果是QueryBuilders.wildcardQuery(“user”, “ding*”)查询，而右边的是constant_score (复合查询)。

{ { "took":4, "took":2, "timed_out":false, "timed_out":false, "_shards":{ "_shards":{ "total":5, "total":5, "successful":5, "successful":5, "skipped":0, "skipped":0, "failed":0 "failed":0 }, }, "hits":{ "hits":{ "total":1, "total":1, "max_score":0.9808292, "max_score":1.5, "hits":[ "hits":[ { { "_index":"twitter", "_index":"twitter", "_type":"_doc", "_type":"_doc", "_id":"12", "_id":"12", "_score":0.9808292, "_score":1.5, "_source":{ "_source":{ "post_date":"2009-11-18T14:12:12", "post_date":"2009-11-18T14:12:12", "message":"test bulk", "message":"test bulk", "user":"dingw" "user":"dingw" } } } } ] ] } }
} }

  

 

  
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2、bool query

布尔查询。bool query里能包含的主要字句类型如下：

2.1 过滤上下文(filter context)中查询对相关性（打分）的影响

在过滤上下文环境的查询字句并不会对相关性产生影响，也就是说过滤上下文中的查询字句，返回的score为0。
例如如下查询示例(使用Java编写)：

public static void testBoolQuery_filterContext_score() {
		RestHighLevelClient client = EsClient.getClient();
		try { SearchRequest searchRequest = new SearchRequest(); searchRequest.indices("twitter"); SearchSourceBuilder sourceBuilder = new SearchSourceBuilder(); sourceBuilder.query( QueryBuilders.boolQuery() .filter(QueryBuilders.termQuery("user", "dingw")) ); searchRequest.source(sourceBuilder); SearchResponse result = client.search(searchRequest, RequestOptions.DEFAULT); System.out.println(result);
		} catch (Throwable e) { e.printStackTrace();
		} finally { EsClient.close(client);
		}
	}

  

 

  
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其返回的结果，其score都为0，结果如下：

{ "took":4, "timed_out":false, "_shards":{ "total":5, "successful":5, "skipped":0, "failed":0 }, "hits":{ "total":3, "max_score":0, "hits":[ { "_index":"twitter", "_type":"_doc", "_id":"22", "_score":0, "_source":{ "post_date":"2018-10-31T14:12:10", "message":"ab and hell", "user":"dingw" } }, { "_index":"twitter", "_type":"_doc", "_id":"12", "_score":0, "_source":{ "post_date":"2009-11-18T14:12:12", "message":"test bulk", "user":"dingw" } }, { "_index":"twitter", "_type":"_doc", "_id":"11", "_score":0, "_source":{ "post_date":"2009-11-19T14:12:12", "message":"test bulk update", "user":"dingw" } } ] }
}

  

 

  
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3、dis max query

该查询方式将所有查询字句进行联合查询(union)，只需要其中一个条件匹配匹配文档，但在计算相关性时不是将所有条件的匹配度(score)相加，而是使使用评分最高的查询条件的score，如果有指定tie_breaker的话，则为最大score 加上 其他score * tie_breaker。dis max query是实现(match query multi fields best_fields)的核心。每个查询，可以指定其评分因子（权重、boost），dis max query使用示例：

	/**
	 * dis max query
	 */
	public static void testDisMaxQuery() {
		RestHighLevelClient client = EsClient.getClient();
		try { SearchRequest searchRequest = new SearchRequest(); searchRequest.indices("twitter"); SearchSourceBuilder sourceBuilder = new SearchSourceBuilder(); sourceBuilder.query( QueryBuilders.disMaxQuery()
// .tieBreaker(0.1f) .add(QueryBuilders.termQuery("user", "dingw").boost(1.2f)) .add(QueryBuilders.termQuery("message", "bulk")) ); searchRequest.source(sourceBuilder); SearchResponse result = client.search(searchRequest, RequestOptions.DEFAULT); System.out.println(result);
		} catch (Throwable e) { e.printStackTrace();
		} finally { EsClient.close(client);
		}
	}

  

 

  
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4、function score query(函数分数查询)

待研究。

5、boosting query

boosting query可以用来提升或降低某些查询条件的权重。举例如下：

GET /_search
{ "query": { "boosting" : { "positive" : { // @1 "term" : { "field1" : "value1" } }, "negative" : { // @2 "term" : { "field2" : "value2" } }, "negative_boost" : 0.2 } }
}

  

 

  
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代码@1：积极的作用，提升其权重。
代码@2：负面的影响，希望降低其权重，其权重值通过negative_boost指定。

复合查询就介绍到这里了。

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文章来源: blog.csdn.net，作者：中间件兴趣圈，版权归原作者所有，如需转载，请联系作者。

原文链接：blog.csdn.net/prestigeding/article/details/102297796