官網searchafter介紹:https://www.elastic.co/guide/en/elasticsearch/reference/7.x/paginate-search-results.html#search-after

官網介紹的查詢返回如下：

{
  "pit_id" : "46ToAwEPbXktaW5kZXgtMDAwMDAxFnVzaTVuenpUVGQ2TFNheUxVUG5LVVEAFldicVdzOFFtVHZTZDFoWWowTGkwS0EAAAAAAAAAAAQURzZzcUszUUJ5U1NMX3Jyak5ET0wBFnVzaTVuenpUVGQ2TFNheUxVUG5LVVEAAA==", 
  
 
"took" : 17,
  "timed_out" : false,
  "_shards" : ...,
  "hits" : {
    "total" : ...,
    "max_score" : null,
    "hits" : [
      ...
      {
        "_index" : "my-index-000001",
        "_id" : "FaslK3QBySSL_rrj9zM5",
        "_score" : null,
        "_source" : ...,
        "sort" : [                                
          4098435132000,
          "FaslK3QBySSL_rrj9zM5"
 

        ]
      }
    ]
  }
}

其中,sort陣列長度為2.

但在實現測試中發現7.4版本es查詢返回時,長度為一

{
  "took" : 191,
  "timed_out" : false,
  "_shards" : {
    "total" : 2,
    "successful" : 2,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 10000,
      "relation" : "gte"
    },
    "max_score" : null
 
,
    "hits" : [
      {
        "_index" : "atc_drg_stat",
        "_type" : "man",
        "_id" : "1000",
        "_score" : null,
        "_source" : {
          "district_code" : "DistrictCode",
          ---------------
        },
        "sort" : [
          1000
        ]

不知道是否是版本變化引起的。

程式碼如下：

@RequestMapping("/searchAfter")
    public void searchAfter() throws IOException {
        String searchAfter =null;
        Object[] objects = new Object[]{};
        try {
            for (int i = 0; i < 100; i++) {
                SearchRequest searchRequest = new SearchRequest(index);
                SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
                searchSourceBuilder.query(matchQuery("year_month", "yearMonth"));
                searchSourceBuilder.size(1000);
                searchSourceBuilder.sort("sort_id", SortOrder.ASC);
                if(objects.length>0) {
                    searchSourceBuilder.searchAfter(objects);
                }
                searchRequest.source(searchSourceBuilder);
                System.out.println(searchRequest.source().toString());
                SearchResponse searchResponse = client.search(searchRequest, RequestOptions.DEFAULT);
                System.out.println(searchResponse);
                SearchHit[] hits = searchResponse.getHits().getHits();
                objects = hits[hits.length-1].getSortValues();

                System.out.println(hits);
            }


        } catch (Exception e) {
            e.printStackTrace();
        }
    }