• 问题描述
    最近在学习ES使用时，通过JavaAPI来实现数据的全量查询，我本来在对应索引里面创建了11条数据，但是使用matchAllQuery()方法进行查询时，发现每次运行都只能获得10条数据，通过探究ES源码，找到了问题所在，ES默认在执行查询或者聚合时都默认返回10条数据，我们可以通过指定size值来修改这个默认值。
• 先创建11条测试数据

public class ES_Doc_Batch_Create {

    private static HttpHost httpHost;
    private static RestClientBuilder builder;
    private static RestHighLevelClient client;

    static {
        // 配置建立http连接的配置信息
        httpHost = new HttpHost("localhost", 9200, "http");
        // 辅助构建RestClient
        builder = RestClient.builder(httpHost);
        // 创建ES高级客户端对象，封装了RestClient对象，并允许发起请求和读取响应
        client = new RestHighLevelClient(builder);
    }

    public static void main(String[] args) throws IOException {
        // 构建BulkRequest对象
        BulkRequest bulkRequest = new BulkRequest();
        // 创建IndexRequest,并添加到bulkRequest中
        IndexRequest indexRequest1 = new IndexRequest().index("user").id("1001").source(XContentType.JSON, "name", "yihao","age","10","sex","男");
        IndexRequest indexRequest2 = new IndexRequest().index("user").id("1002").source(XContentType.JSON, "name", "erhao","age","10","sex","女");
        IndexRequest indexRequest3 = new IndexRequest().index("user").id("1003").source(XContentType.JSON, "name", "sanhao","age","11","sex","男");
        IndexRequest indexRequest4 = new IndexRequest().index("user").id("1004").source(XContentType.JSON, "name", "sihao","age","12","sex","女");
        IndexRequest indexRequest5 = new IndexRequest().index("user").id("1005").source(XContentType.JSON, "name", "wuhao","age","12","sex","女");
        IndexRequest indexRequest6 = new IndexRequest().index("user").id("1006").source(XContentType.JSON, "name", "liuhao","age","13","sex","女");
        IndexRequest indexRequest7 = new IndexRequest().index("user").id("1007").source(XContentType.JSON, "name", "qihao","age","14","sex","女");
        IndexRequest indexRequest8 = new IndexRequest().index("user").id("1008").source(XContentType.JSON, "name", "bahao","age","15","sex","女");
        IndexRequest indexRequest9 = new IndexRequest().index("user").id("1009").source(XContentType.JSON, "name", "jiuhao","age","16","sex","女");
        IndexRequest indexRequest10 = new IndexRequest().index("user").id("1010").source(XContentType.JSON, "name", "shihao","age","17","sex","男");
        IndexRequest indexRequest11 = new IndexRequest().index("user").id("1011").source(XContentType.JSON, "name", "shiyihoa","age","20","sex","男");
        bulkRequest.add(indexRequest1);
        bulkRequest.add(indexRequest2);
        bulkRequest.add(indexRequest3);
        bulkRequest.add(indexRequest4);
        bulkRequest.add(indexRequest5);
        bulkRequest.add(indexRequest6);
        bulkRequest.add(indexRequest7);
        bulkRequest.add(indexRequest8);
        bulkRequest.add(indexRequest9);
        bulkRequest.add(indexRequest10);
        bulkRequest.add(indexRequest11);
        // 执行批量新增的方法
        BulkResponse response = client.bulk(bulkRequest, RequestOptions.DEFAULT);
        // 获取响应信息
        System.out.println("花费时间:"+response.getTook());
        // 关闭连接
        try {
            client.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

• 问题测试代码

public class ES_Doc_OrderBy {

    private static HttpHost httpHost = null;
    private static RestClientBuilder builder = null;
    private static RestHighLevelClient client = null;

    static {
        // 配置建立http连接信息
        httpHost = new HttpHost("localhost", 9200, "http");
        // 辅助构建RestClient
        builder = RestClient.builder(httpHost);
        // 创建ES高级客户端对象，进一步封装了RestClient，并允许发起请求和读取响应
        client = new RestHighLevelClient(builder);
    }

    public static void main(String[] args) {
        // 创建SearchRequest对象,并指定要操作的索引对象
        SearchRequest request = new SearchRequest("user");
        // 构建查询条件，通过SearchSourceBuilder
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        // ----------------
        // 设置匹配所有的查询条件
        searchSourceBuilder.query(QueryBuilders.matchAllQuery());
        // 将查询条件保存到查询请求中
        request.source(searchSourceBuilder);
        // 执行查询操作
        SearchResponse response = null;
        try {
            response = client.search(request, RequestOptions.DEFAULT);
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 获取响应信息
        System.out.println("查询到的数据条数："+response.getHits().getTotalHits());
        System.out.println("查询到的数据内容：");
        for (SearchHit hit : response.getHits()) {
            System.out.println(hit.getSourceAsString());
        }
        // 关闭连接
        try {
            client.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

• 解决方式
    我们只需要根据自己的需要调整size大小即可，下面是更改后的代码，运行就可以获得指定size大小的数据了。

public class ES_Doc_OrderBy {

    private static HttpHost httpHost = null;
    private static RestClientBuilder builder = null;
    private static RestHighLevelClient client = null;

    static {
        // 配置建立http连接信息
        httpHost = new HttpHost("localhost", 9200, "http");
        // 辅助构建RestClient
        builder = RestClient.builder(httpHost);
        // 创建ES高级客户端对象，进一步封装了RestClient，并允许发起请求和读取响应
        client = new RestHighLevelClient(builder);
    }

    public static void main(String[] args) {
        // 创建SearchRequest对象,并指定要操作的索引对象
        SearchRequest request = new SearchRequest("user");
        // 构建查询条件，通过SearchSourceBuilder
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        // ----------------
        // 设置匹配所有的查询条件
        searchSourceBuilder.query(QueryBuilders.matchAllQuery());
        searchSourceBuilder.size(20);
        // 将查询条件保存到查询请求中
        request.source(searchSourceBuilder);
        // 执行查询操作
        SearchResponse response = null;
        try {
            response = client.search(request, RequestOptions.DEFAULT);
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 获取响应信息
        System.out.println("查询到的数据条数："+response.getHits().getTotalHits());
        System.out.println("查询到的数据内容：");
        for (SearchHit hit : response.getHits()) {
            System.out.println(hit.getSourceAsString());
        }
        // 关闭连接
        try {
            client.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}