ElasticSearch 6.x 学习笔记：32.Java API之复合查询

https://www.elastic.co/guide/en/elasticsearch/client/java-api/6.1/java-compound-queries.html

Compound queriesedit Compound queries wrap other compound or leaf queries, either to combine their results and scores, to change their behaviour, or to switch from query to filter context.

1、constant_score query

A query which wraps another query, but executes it in filter context. All matching documents are given the same “constant” _score.

constantScoreQuery(termQuery("name","kimchy")).boost(2.0f);

2、bool query

The default query for combining multiple leaf or compound query clauses, as must, should, must_not, or filter clauses. The must and should clauses have their scores combined — the more matching clauses, the better — while the must_not and filter clauses are executed in filter context.

boolQuery()
        .must(termQuery("content", "test1"))                 
        .must(termQuery("content", "test4"))                 
        .mustNot(termQuery("content", "test2"))              
        .should(termQuery("content", "test3"))               
        .filter(termQuery("content", "test5"));

3、dis_max query

A query which accepts multiple queries, and returns any documents which match any of the query clauses. While the bool query combines the scores from all matching queries, the dis_max query uses the score of the single best- matching query clause.

disMaxQuery()
        .add(termQuery("name", "kimchy"))                    
        .add(termQuery("name", "elasticsearch"))             
        .boost(1.2f)                                         
        .tieBreaker(0.7f);

4、function_score query

Modify the scores returned by the main query with functions to take into account factors like popularity, recency, distance, or custom algorithms implemented with scripting.

To use ScoreFunctionBuilders just import them in your class:

import static org.elasticsearch.index.query.functionscore.ScoreFunctionBuilders.*;

FilterFunctionBuilder[] functions = {
        new FunctionScoreQueryBuilder.FilterFunctionBuilder(
                matchQuery("name", "kimchy"),                
                randomFunction()),                           
        new FunctionScoreQueryBuilder.FilterFunctionBuilder(
                exponentialDecayFunction("age", 0L, 1L))     
};
functionScoreQuery(functions);

5、boosting query

Return documents which match a positive query, but reduce the score of documents which also match a negative query.

boostingQuery(
            termQuery("name","kimchy"),                      
            termQuery("name","dadoonet"))                    
        .negativeBoost(0.2f);