ElasticSearch序列 - SpringBoot整合ES：根据指定的 ids 查询

1. ElasticSearch 根据 ids 查询文档

① 索引文档，构造数据

PUT /my_index/_doc/1
{
  "price":10
}

PUT /my_index/_doc/2
{
  "price":20
}

PUT /my_index/_doc/3
{
  "price":30
}

② 查询文档 id 为 1 或者 2 的文档：

GET /my_index/_search
{
  "query": {
    "ids": {
      "values": [1,2]
    }
  }
}

{
  "took" : 1,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "my_index",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 1.0,
        "_source" : {
          "price" : 10
        }
      },
      {
        "_index" : "my_index",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 1.0,
        "_source" : {
          "price" : 20
        }
      }
    ]
  }
}

我们索引文档时，文档的id为整型，为什么查询出来的文档 id为字符串类型呢？如果我们使用字符串类型的文档id查询呢？

GET /my_index/_search
{
  "query": {
    "ids": {
      "values": ["1","2"]
    }
  }
}

{
  "took" : 2,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "my_index",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 1.0,
        "_source" : {
          "price" : 10
        }
      },
      {
        "_index" : "my_index",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 1.0,
        "_source" : {
          "price" : 20
        }
      }
    ]
  }
}

可以看到仍然可以查询到匹配的文档。

在Elasticsearch中，文档ID可以是任何字符串类型，包括数字、字母、符号等。即使您在索引文档时使用了整数作为ID，Elasticsearch也会将其转换为字符串类型，并将其存储在内部索引中。当您查询文档时，Elasticsearch会将文档ID作为字符串类型返回。

如果您需要将查询结果中的文档ID转换为整数类型，可以在查询结果中进行转换。例如，在使用Java API执行查询时，您可以使用以下代码将文档ID转换为整数类型：

SearchResponse response = client.prepareSearch("my_index")
        .setQuery(QueryBuilders.matchAllQuery())
        .get();

for (SearchHit hit : response.getHits().getHits()) {
    int id = Integer.parseInt(hit.getId());
    // do something with the integer ID
}

在上面的代码中，我们首先执行一个查询，并使用getHits方法获取查询结果。然后，我们遍历查询结果中的每个文档，并使用Integer.parseInt方法将文档ID转换为整数类型。

2. SpringBoot整合ES实现 ids 查询

GET /my_index/_search
{
  "query": {
    "ids": {
      "values": [1,2]
    }
  }
}

@Slf4j
@Service
public class ElasticSearchImpl {

    @Autowired
    private RestHighLevelClient restHighLevelClient;

    public void searchUser() throws IOException {
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();

        // ids 查询
        IdsQueryBuilder idsQueryBuilder = new IdsQueryBuilder();
        // IdsQueryBuilder addIds(String... ids) 
        idsQueryBuilder.addIds("1", "2");
        searchSourceBuilder.query(idsQueryBuilder);

        SearchRequest searchRequest = new SearchRequest(new String[]{"my_index"},searchSourceBuilder);
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);
        System.out.println(searchResponse);
    }
}

如果我们想根据 ids 去查询文档的话，一般会使用 terms 查询：

GET /my_index/_search
{
  "query": {
    "terms": {
      "_id": [
        "1",
        "2"
      ]
    }
  }
}

需要注意的是主键为_id，而不是id，如果使用id则查询结果会为空。

@Slf4j
@Service
public class ElasticSearchImpl {

    @Autowired
    private RestHighLevelClient restHighLevelClient;

    public void searchUser() throws IOException {
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();

        // terms 查询
        List<String> ids = Arrays.asList("1","2");
        TermsQueryBuilder termsQueryBuilder = new TermsQueryBuilder("_id",ids);
        searchSourceBuilder.query(termsQueryBuilder);

        SearchRequest searchRequest = new SearchRequest(new String[]{"my_index"},searchSourceBuilder);
        SearchResponse searchResponse = restHighLevelClient.search(searchRequest, RequestOptions.DEFAULT);
        System.out.println(searchResponse);
    }
}

{
  "took" : 2,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 2,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "my_index",
        "_type" : "_doc",
        "_id" : "1",
        "_score" : 1.0,
        "_source" : {
          "price" : 10
        }
      },
      {
        "_index" : "my_index",
        "_type" : "_doc",
        "_id" : "2",
        "_score" : 1.0,
        "_source" : {
          "price" : 20
        }
      }
    ]
  }
}