[大数据]基于Mysql理解 Java RestHighLevelClient ES查询语句

//起手构建请求
SearchRequest request = new SearchRequest();

request常用操作:

1. 指定索引,可传入多个索引，支持通配符*
   request.indices(String[] tables) 等同于 select xx from table1，table2…

//构建查询
SearchSourceBuilder builder = new SearchSourceBuilder();

builder常用操作:

1. 分页查询
   builder.from(0)
   builder.size(10) 等同于 limit 1,10
2. 排序
   builder.sort(“age”, SortOrder.DESC) 等同于 order by age desc
3. 过滤字段
   String[] includes = {“name”};
   String[] excludes = {};
   query3.fetchSource(includes, excludes); 等同于 select name from index

//给SearchSourceBuilder设置查询条件

1. builder.query(QueryBuilder queryBuilder);
   // 聚合查询操作

2. builder.aggregation(AggregationBuilder aggregation);

   常用QueryBuilder :

   1. QueryBuilders.matchAllQuery() 等同于 select * from index
   2. QueryBuilders.matchQuery() 等同于 select * from index where xxx
   3. QueryBuilders.boolQuery() 布尔类型查询，可传入多个各种QueryBuilder，构建更复杂的查询，每个QueryBuilder 相当于加了个()
   4. QueryBuilders.rangeQuery() 范围查询 等同于 where flied < and > filed
   5. QueryBuilders.fuzzyQuery() 模糊查询 .fuzziness() 函数指定模糊字符偏移量

   常用AggregationBuilder :

   1. AggregationBuilders.max(“maxAge”).field(“age”); 最大值，等同于函数 select max(“age”) as maxAge
   2. AggregationBuilders.terms(“ageGroup”).field(“age”); 分组查询，等同于 group by age

QueryBuilders.boolQuery()常用函数:
1. 多个must(QueryBuilder)          等同于  ( QueryBuilder1 ) and ( QueryBuilder2 ) 多个must 取 ∩ 交集
2. 多个should(QueryBuilder)        等同于  ( QueryBuilder1 ) or  ( QueryBuilder2 )  多个should 取 ∪ 并集
3. 单个must/should                 等同于  where xx = xx，单个must/should传入的QueryBuilder，符合这个条件

        //must -> SQL ‘=’ ‘and’
        boolQueryBuilder.must(QueryBuilders.matchQuery("age", "24"));
        //should -> SQL ‘or’
        boolQueryBuilder.should(QueryBuilders.matchQuery("age", "24"));
        boolQueryBuilder.should(QueryBuilders.matchQuery("age", "25"));
        
        
QueryBuilders.rangeQuery()常用函数:  
4. rangeQuery.gte("25");           大于，对于指定字段进行大小判断
5. rangeQuery.lte("30");           小于，对于指定字段进行大小判断

request.source(query);

SearchResponse response = client.search(request, RequestOptions.DEFAULT);

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