Java 实现对ES的Scroll读以及分片Scroll读--全量数据读取-Toy模板网

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Java 实现对ES的Scroll读以及分片Scroll读

本文实现的是使用Java对ES索引全量数据的读取操作。ES版本是7.14。采用两种方式，一种是不分片读，一种是分片读。
对ES实现全量读取需要依赖到ES所提供的API，这里需要添加两个依赖

    <dependency>
      <groupId>org.elasticsearch.client</groupId>
      <artifactId>elasticsearch-rest-high-level-client</artifactId>
      <version>7.14</version>
    </dependency>

    <dependency>
      <groupId>org.elasticsearch</groupId>
      <artifactId>elasticsearch</artifactId>
      <version>7.14</version>
      <scope>compile</scope>
    </dependency>

方式一不分片Scroll读取

public RestHighLevelClient initClient(String ip,String port,String scheme,String username,String password)
{
    int intPort = Integer.parseInt(port);
    HttpHost host=new HttpHost( ip, intPort, scheme);
    RestClientBuilder builder=RestClient.builder(host);
    CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
    credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials(username,password));
    builder.setHttpClientConfigCallback(f -> f.setDefaultCredentialsProvider(credentialsProvider));
    RestHighLevelClient client = new RestHighLevelClient(builder);
    return client;
}
    
public void testReadSpeed() throws IOException {
		//与es节点建立连接
        RestHighLevelClient esClient = initClient("192.168.11.137","9200","http","elastic","123456");
        
        int scrollSize = 1000;//一次读取的doc数量
        SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
        searchSourceBuilder.query(QueryBuilders.matchAllQuery());//读取全量数据
        searchSourceBuilder.size(scrollSize);
        Scroll scroll1 = new Scroll(TimeValue.timeValueMinutes(3));//设置一次读取的最大连接时长

        String index1 = "alltype_test";//读取的索引名称
        SearchRequest searchRequest1 = new SearchRequest(index1);
        searchRequest1.types("_doc");
        searchRequest1.source(searchSourceBuilder);
        searchRequest1.scroll(scroll1);
        SearchResponse searchResponse1 = null;
        searchResponse1 = esClient.search(searchRequest1,RequestOptions.DEFAULT);
        String scrollId1 = searchResponse1.getScrollId();
        SearchHit[] hits1 = searchResponse1.getHits().getHits();

        long st = System.currentTimeMillis();

        while (hits1.length > 0) {
            try {
                SearchScrollRequest searchScrollRequest1 = new SearchScrollRequest(scrollId1);
                searchScrollRequest1.scroll(scroll1);
                SearchResponse searchScrollResponse1 = null;

                searchScrollResponse1 = esClient.searchScroll(searchScrollRequest1,RequestOptions.DEFAULT);
                scrollId1 = searchScrollResponse1.getScrollId();
                hits1 = searchScrollResponse1.getHits().getHits();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        ClearScrollRequest clearScrollRequest = new ClearScrollRequest();
        clearScrollRequest.addScrollId(scrollId1);
        try {
            esClient.clearScroll(clearScrollRequest,RequestOptions.DEFAULT);
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println("读取用时:" + (System.currentTimeMillis() - st));
    }

方式二分片读取

分片就是将一个索引的全量数据分成几块，对每个块分别生成一个Scroll对象来读取。分片的数量最佳是根据索引的shards数来定。

/**
*读线程
*/
class ReadTread extends Thread{
        private RestHighLevelClient esClient;
        private SliceBuilder slice;
        private int scrollSize;
        private String index;

        public ReadTread(RestHighLevelClient esClient, SliceBuilder slice, int scrollSize, String index){
            this.esClient = esClient;
            this.slice = slice;
            this.scrollSize = scrollSize;
            this.index = index;
        }

        @Override
        public void run() {
            SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
            searchSourceBuilder.query(QueryBuilders.matchAllQuery());
            searchSourceBuilder.size(scrollSize);
            Scroll scroll1 = new Scroll(TimeValue.timeValueMinutes(3));

            SearchRequest searchRequest1 = new SearchRequest(index);
            searchRequest1.types("_doc");
            searchRequest1.source(searchSourceBuilder.slice(slice).sort("_doc"));
            searchRequest1.scroll(scroll1);
            SearchResponse searchResponse1 = null;
            try {
                searchResponse1 = esClient.search(searchRequest1,RequestOptions.DEFAULT);
            } catch (IOException e) {
                e.printStackTrace();
            }
            String scrollId1 = searchResponse1.getScrollId();
            SearchHit[] hits1 = searchResponse1.getHits().getHits();

            while (hits1.length > 0) {
                try {
                    SearchScrollRequest searchScrollRequest1 = new SearchScrollRequest(scrollId1);
                    searchScrollRequest1.scroll(scroll1);
                    SearchResponse searchScrollResponse1 = null;

                    searchScrollResponse1 = esClient.searchScroll(searchScrollRequest1,RequestOptions.DEFAULT);
                    scrollId1 = searchScrollResponse1.getScrollId();
                    hits1 = searchScrollResponse1.getHits().getHits();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            ClearScrollRequest clearScrollRequest = new ClearScrollRequest();
            clearScrollRequest.addScrollId(scrollId1);
            try {
                esClient.clearScroll(clearScrollRequest,RequestOptions.DEFAULT);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

public RestHighLevelClient initClient(String ip,String port,String scheme,String username,String password)
{
    int intPort = Integer.parseInt(port);
    HttpHost host=new HttpHost( ip, intPort, scheme);
    RestClientBuilder builder=RestClient.builder(host);
    CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
    credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials(username,password));
    builder.setHttpClientConfigCallback(f -> f.setDefaultCredentialsProvider(credentialsProvider));
    RestHighLevelClient client = new RestHighLevelClient(builder);
    return client;
}

public void testSearchScrollSlice() throws IOException {
        ScheduledExecutorService executor = Executors.newScheduledThreadPool(4);//创建一个大小为4的线程池
        RestHighLevelClient esClient = initClient("192.168.11.137","9200","http","elastic","123456");
        
        int scrollSize = 1000;
        String index1 = "alltype";
        GetSettingsRequest settingsRequest = new GetSettingsRequest().indices(index1);
		//获取索引的shards数量
        settingsRequest.names("index.number_of_shards");
        GetSettingsResponse getSettingsResponse = esClient.indices().getSettings(settingsRequest,RequestOptions.DEFAULT);
        String num = getSettingsResponse.getSetting(index1, "index.number_of_shards");
        int shardnum = Integer.parseInt(num);

        long st = System.currentTimeMillis();

        for(int i=0; i<shardnum; i++) {
            SliceBuilder slice = new SliceBuilder(i,shardnum);
            ReadTread readTread = new ReadTread(esClient, slice, scrollSize, index1, count);
            executor.schedule(readTread, 0, TimeUnit.MILLISECONDS);
        }

        executor.shutdown();
        while (!executor.isTerminated()) {
        }

        System.out.println("读取用时:" + (System.currentTimeMillis() - st));

    }