ES游标使用

      最近有一个需求，索引中添加了2个字段，需要对历史数据进行割接，调查现网仅有800多条数据，开发环境600多条数据，所以代码中写死了size为2000条，一次割接完，但是转到测试环境出了问题，测试说有数据没割接，查询一下原来测试环境有2万多条数据，在网上查询了解到ES一次最多支持查询1万条记录，显然一次是割接不完的，即使一次可以割接完也是不行的，毕竟数据量太大，不适宜一次性加入到内存中，好在ES支持游标查询，下面是ES的游标用法

/**
 * 通过游标查询数据
 * 
 * indices 索引
 * @throws IOException
 */
public static void searchByScroll(String indices) throws IOException {
	SearchRequest request = new SearchRequest(indices);
	SearchSourceBuilder build = new SearchSourceBuilder();
	build.query(QueryBuilders.termQuery("age","21"));
        // 设置每次查询的数据集大小
	build.size(1);
	build.timeout(new TimeValue(60, TimeUnit.SECONDS));
	request.source(build);
        // 游标时长
	Scroll scroll = new Scroll(TimeValue.timeValueMillis(10l));
	request.scroll(scroll);
	SearchResponse response = restHighLevelClient.search(request,RequestOptions.DEFAULT);
	SearchHit[] hit = response.getHits().getHits();
	for (int i = 0;i<hit.length;i++){
	    System.out.println(hit[i].getSourceAsMap().get("name"));
	}
        
	String scrollId = response.getScrollId();
	SearchScrollRequest searchScrollRequest;
	while(hit != null && hit.length > 0) {   
	    searchScrollRequest = new SearchScrollRequest(scrollId);
	    searchScrollRequest.scroll(scroll);
	    response = restHighLevelClient.scroll(searchScrollRequest,RequestOptions.DEFAULT);
	    hit = response.getHits().getHits();
	    for (int i = 0;i<hit.length;i++){
		System.out.println(hit[i].getSourceAsMap().get("name"));
	    }
       }
}