免费的黄冈网站有哪些平台可以用微信支付,正规刷手机单做任务网站,网站建设汇编资料,百度大盘指数一、scroll说明和使用场景
scroll的使用场景#xff1a;大数据量的检索和操作
scroll顾名思义#xff0c;就是游标的意思#xff0c;核心的应用场景就是遍历 elasticsearch中的数据#xff1b;
通常我们遍历数据采用的是分页#xff0c;elastcisearch还支持from size的…一、scroll说明和使用场景
scroll的使用场景大数据量的检索和操作
scroll顾名思义就是游标的意思核心的应用场景就是遍历 elasticsearch中的数据
通常我们遍历数据采用的是分页elastcisearch还支持from size的方式进行分页查询使用 from and size 的深度分页比如说 ?size10from10000因为 100,000 排序的结果必须从每个分片上取出并重新排序最后返回 10 条。这个过程需要对每个请求页重新进行提取排序效率很低消耗很大所以默认的最大可分页的数据是10000超过10000是不建议的
使用
通过在url末尾带上scroll1m表示开启一个游标1m表示游标的有效期为1分钟
POST /record/_search?scroll1m
{from: 0,size: 20
}返回结果中会把scroll的id带上再次查询的时候直接用scroll id查询即可 POST /_search/scroll
{scroll : 1m, scroll_id : FGluY2x1ZGVfY29udGV4dF91dWlkDnF1ZXJ5VGhlbkZldGNoAhZuYmpMbVpwWFRUMnNFMUFFSHlSMHB3AAAAAALBy_0WUWxrNTRTaWNUcy1sOHQ0VUo5dzF6dxZoemFkZTlMeFQ4MmoyOW5SUG8ybE53AAAAAAN6ip8WMmk5TWZlQ21RQnFsNURwaXRzSGhCdw
}二、基于ElasticsearchRestTemplate的实现
这里我们定义了一个template如下主要作用就是实现一个基于scroll的数据遍历模板屏蔽开启scroll 以及 scroll遍历所有数据通过ConsumerT钩子函数进行数据处理
import lombok.extern.slf4j.Slf4j;
import org.elasticsearch.index.query.BoolQueryBuilder;
import org.elasticsearch.index.query.QueryBuilders;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.elasticsearch.core.ElasticsearchRestTemplate;
import org.springframework.data.elasticsearch.core.SearchHit;
import org.springframework.data.elasticsearch.core.SearchScrollHits;
import org.springframework.data.elasticsearch.core.mapping.IndexCoordinates;
import org.springframework.data.elasticsearch.core.query.NativeSearchQueryBuilder;import java.util.List;
import java.util.concurrent.*;/*** scrollTemplate 模板用于遍历整个Index的数据* author xiuzhu* Date 2023/7/28 13:12*/
Slf4j
public class ElasticSearchScrollTemplateT {ExecutorService executorService new ThreadPoolExecutor(1, 4,30,TimeUnit.SECONDS,new LinkedBlockingQueueRunnable(5),Executors.defaultThreadFactory(),new ThreadPoolExecutor.CallerRunsPolicy());ElasticsearchRestTemplate elasticSearchRestTemplate;ClassT cls;String indexName;public ElasticSearchScrollTemplate(ElasticsearchRestTemplate template,ClassT cls,String indexName) {this.elasticSearchRestTemplate template;this.cls cls;this.indexName indexName;}FunctionalInterfacepublic interface ConsumerT {public void accept(ListT objects);}public void execute(ConsumerT consumer) {//构建查询条件NativeSearchQueryBuilder query new NativeSearchQueryBuilder();BoolQueryBuilder queryBuilder QueryBuilders.boolQuery();query.withPageable(PageRequest.of(0, 300));query.withQuery(queryBuilder);//保留0.5分钟long scrollTimeInMillis 30*1000;IndexCoordinates recordIndex IndexCoordinates.of(indexName);SearchScrollHitsT hits elasticSearchRestTemplate.searchScrollStart(scrollTimeInMillis, query.build(), cls, recordIndex);// scrollIdString scrollId hits.getScrollId();ListT recordEntityList hits.stream().map(SearchHit::getContent).toList();long total 0L;log.info( began scroll index{} , indexName);executorService.submit(()-{consumer.accept(recordEntityList);});total total recordEntityList.size();log.info( has scroll index{} total{} , indexName, total);while (!hits.isEmpty()) {hits elasticSearchRestTemplate.searchScrollContinue(scrollId, scrollTimeInMillis, cls, recordIndex);ListT entities hits.stream().map(SearchHit::getContent).toList();executorService.submit(()-{consumer.accept(entities);});total total entities.size();try {//给系统留GC时间不然容易内存溢出Thread.sleep(300);} catch (InterruptedException e) {log.error(sleep error, e);}log.info( has scroll index{} total{} , indexName, total);}log.info( end scroll index{} , indexName);}
}使用参考
Resource(name elasticSearchRestTemplate)ElasticsearchRestTemplate elasticsearchRestTemplate;new ElasticSearchScrollTemplate(elasticsearchRestTemplate,RecordEntity.class,record)).execute((entities)-{entities.forEach(item-{//这里进行数据的处理比如修改数据recordEntityService.save(item);log.info(tag update success record{} api{}, item.getId());});});本文由mdnice多平台发布
