【ES】ES中的join方案一（Nested类型，基于6.3版本的java实现）

2024-07-03 10:42| 来源: 网络整理| 查看: 265

菜鸡一只，国庆真是玩了好几天，等到快上班的时候才开始又学习，找状态

本文来讲讲ES中的Join方案！

在数据库中，join是非常常见的操作！

其实就是将两张表的数据合并到一起，然后查询出结果数据，当然最后可能还需要一些过滤，这是数据库中的概念

在ES中也有join的方案，ES提供了两种api：

1、使用Nested结构存储（查询）数据

2、通过设置字段的type为join，然后使用hasChild和hasParent查询数据

官网相关链接：

https://www.elastic.co/guide/en/elasticsearch/reference/6.3/parent-join.htmlhttps://www.elastic.co/guide/en/elasticsearch/reference/6.3/query-dsl-nested-query.htmlhttps://www.elastic.co/guide/en/elasticsearch/reference/6.3/query-dsl-has-child-query.htmlhttps://www.elastic.co/guide/en/elasticsearch/reference/6.3/query-dsl-has-parent-query.htmlhttps://www.elastic.co/guide/en/elasticsearch/reference/6.3/query-dsl-parent-id-query.htmlhttps://www.elastic.co/guide/en/elasticsearch/client/java-api/6.3/java-joining-queries.html

举个很现实的例子：

表A：blog_new（博客）

表B：comments（评论）

他们之间的关系是一个问题会有多个答案，将这部分数据录入到ES中提供搜索

blog_new | | comments

方案一：

通过Nested解决问题（把问题和答案当做一个document文档插入ES中）：

##设置mapping PUT blog_new { "mappings": { "blog": { "properties": { "title": { "type": "text" }, "body": { "type": "text" }, "tags": { "type": "keyword" }, "comments": { "type": "nested", "properties": { "name": { "type": "text" }, "comment": { "type": "text" }, "age": { "type": "short" }, "stars": { "type": "short" }, "date": { "type": "date" } } } } } } } ##放进两条测试数据 PUT blog_new/blog/1 { "title": "Nest eggs", "body": "Making your money work...", "tags": [ "cash", "shares" ], "comments": [ { "name": "John Smith", "comment": "Great article", "age": 28, "stars": 4, "date": "2014-09-01" }, { "name": "Alice White", "comment": "More like this please", "age": 31, "stars": 5, "date": "2014-10-22" } ] } POST blog_new/blog/2 { "title": "Hero", "body": "Hero test body...", "tags": ["Heros", "happy"], "comments": [ { "name": "steve", "age": 24, "stars": 5, "comment": "Nice article..", "date": "2014-10-22" } ] }

当我们对于这样的数据结构进行增删改查的时候，需要通过nested关键字来处理

1、查询数据：

##查询查询评论的人的名称匹配john和他/她的年龄是28岁 GET blog_new/blog/_search { "query": { "bool": { "must": [ { "nested": { "path": "comments", "query": { "bool": { "must": [ { "match": { "comments.name": "john" } }, { "match": { "comments.age": 28 } } ] } } } } ] } } }

2、新增数据：

##可以把整条数据全部读出来，然后整条update， POST blog_new/blog/2 { "title": "Hero", "body": "Hero test body...", "tags": ["Heros", "happy"], "comments": [ { "name": "steve", "age": 24, "stars": 5, "comment": "Nice article..", "date": "2014-10-22" } ] } ##也可以通过script来更新部分（某个字段），还是比较麻烦的 POST blog_new/blog/2/_update { "script" : { "source": "ctx._source.tags.add(params.tag)", "lang": "painless", "params" : { "tag" : "blue" } } } POST blog_new/blog/2/_update { "script": { "source": "ctx._source.comments.add(params.commentuser)", "lang": "painless", "params": { "commentuser": { "name": "steve", "age": 70, "stars": 5, "comment": "very very good article...", "date": "2014-10-22" } } } }

3、删除数据：

##删除文档id=1的所有名字叫做John Smith的comments（评论） POST blog_new/blog/1/_update { "script": { "lang": "painless", "source": "ctx._source.comments.removeIf(it -> it.name == 'John Smith');" } }

4、修改数据：

##修改文档id=2，名字叫做steve的comments（评论），年龄修改为75，评论内容修改为very very good article... POST blog_new/blog/2/_update { "script": { "source": "for(e in ctx._source.comments){if (e.name == 'steve') {e.age = 75; e.comment= 'very very good article...';}}" } }

5、与之对应的JavaAPI：

public static void main(String[] args) throws Exception { ElasticConfigration es = new ElasticConfigration(); //自己写的es的TransportClient创建 es.initialize(); //获得client对象 TransportClient client = es.client(); testNestedQuery(client); } public static void testNestedQuery(TransportClient client) { NestedQueryBuilder nestedQueryBuilder = new NestedQueryBuilder("comments", QueryBuilders.boolQuery() .must(QueryBuilders.matchQuery("comments.name", "john")) .must(QueryBuilders.matchQuery("comments.age",28)),ScoreMode.None); SearchResponse searchResponse = client.prepareSearch("blog_new") .setTypes("blog") .addSort("_score", SortOrder.DESC) .setQuery(nestedQueryBuilder) .setFrom(0).setSize(50).execute().actionGet(); printSearchResponse(searchResponse); } public static void testNestedUpdateQuery(TransportClient client) throws IOException { // UpdateResponse updateResponse = client.prepareUpdate("blog_new","blog","2").setScript( // new Script("for(e in ctx._source.comments){if (e.name == 'steve') {e.age = 25; e.comment= 'very very good article...';}}")).execute().actionGet(); // System.out.println(updateResponse.status()); /** * 如果要插入一个新的comment,需要在params的Map中,插入JSONObject对象 * 直接使用json格式的字符串,会报错：tried to parse field [null] as object, but found a concrete value */ JSONObject jsonObject = new JSONObject(); jsonObject.put("name","ll"); jsonObject.put("age",75); jsonObject.put("stars",5); jsonObject.put("comment","very very good article..."); jsonObject.put("date","2014-10-22"); jsonObject.put("name","ll"); HashMap hashMap = new HashMap(); hashMap.put("commentuser",jsonObject); UpdateResponse updateResponse = client .prepareUpdate("blog_new","blog","2") .setScript(new Script(ScriptType.INLINE,"painless", "ctx._source.comments.add(params.commentuser)", hashMap)) .execute().actionGet(); System.out.println(updateResponse.status()); } public static void printSearchResponse( SearchResponse searchResponse) { // 命中的记录数 long totalHits = searchResponse.getHits().getTotalHits(); System.out.println("totalHits:" + totalHits); for (SearchHit searchHit : searchResponse.getHits()) { // 打分 float score = searchHit.getScore(); System.out.println("score:" + score); // 文章id int id = Integer.parseInt(searchHit.getId()); System.out.println("doc_id:" + id); String sourceAsString = searchHit.getSourceAsString(); System.out.println(sourceAsString); } }

本文参考了一些其他人的博客和官网，官网列在最前面了，建议大家都去看下，有助于整合思路，有一篇文章我觉得写的超好的，大家也可以看看，如下：

《干货 | Elasticsearch Nested类型深入详解》：https://blog.csdn.net/laoyang360/article/details/82950393（作者：铭毅天下）

好，方案二，我在下一篇文章里面再写吧，不然文章太长，看的我自己都头疼，更别说各位看官了~ 老话，菜鸡一只，如果有任何问题，欢迎留言！

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