这篇文章主要介绍“ElasticSearch如何实现查询所有数据”，在日常操作中，相信很多人在ElasticSearch如何实现查询所有数据问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答”ElasticSearch如何实现查询所有数据”的疑惑有所帮助！接下来，请跟着小编一起来学习吧！

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1，分页查询所有，但最多能查10000 条记录，超过就会报错

 public List getAll(String index, String type, QueryBuilder queryBuilder, Class tClass)  {
        SearchResponse searchResponse = buildRequest(index, type, queryBuilder, 0).get();
        SearchHits hits = searchResponse.getHits();
        int total = (int) hits.totalHits;

        List result = new ArrayList<>(total);
        addToResult(hits,result,tClass);

        int pagesize = 1000;
        int page = total / pagesize;
        if(total % pagesize != 0){
            page++;
        }
        for (int i = 2; i <= page; i++) {
            int from = (i - 1) * pagesize;
            searchResponse = buildRequest(index, type, queryBuilder, from).get();
            hits = searchResponse.getHits();
            addToResult(hits,result,tClass);
        }
        return result;
    }




    private SearchRequestBuilder buildRequest(String index,String type,QueryBuilder queryBuilder,int from) {
        TransportClient client = elasticSearchManager.getClient("ad");
        int pagesize = 1000;
        SearchRequestBuilder builder = client
                .prepareSearch(index)
                .setTypes(type)
                .setFrom(from)
                .setSize(pagesize)
                .setQuery(queryBuilder);
        log.info("ElasticsearchDAO query string：\nGET {}/{}/_search\n{} ", index, type, builder.toString());
        return builder;
    }

2,利用scroll，这是官方推荐的方式

import lombok.extern.slf4j.Slf4j;
import org.elasticsearch.action.search.SearchRequestBuilder;
import org.elasticsearch.action.search.SearchResponse;
import org.elasticsearch.client.transport.TransportClient;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.index.query.BoolQueryBuilder;
import org.elasticsearch.index.query.QueryBuilder;
import org.elasticsearch.index.query.QueryBuilders;
import org.elasticsearch.search.SearchHit;
import org.elasticsearch.search.SearchHits;
import org.elasticsearch.search.aggregations.Aggregation;
import org.elasticsearch.search.aggregations.AggregationBuilder;
import org.elasticsearch.search.aggregations.Aggregations;
import org.elasticsearch.search.aggregations.bucket.MultiBucketsAggregation;
import org.elasticsearch.search.aggregations.bucket.terms.Terms;
import org.elasticsearch.search.aggregations.metrics.NumericMetricsAggregation;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.util.CollectionUtils;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutionException;

@Slf4j
@Component
public class ElasticsearchDAO {

    @Autowired
    private ElasticSearchManager elasticSearchManager;

    private int pagesize = 10000;

    /**
     * es 游标有效期
     */
    private final int ES_SCROLL_TIME = 10;

    public List search(SearchRequest req) throws ExecutionException, InterruptedException {
        BoolQueryBuilder boolQuery = req.getQueryBuilder();

        List result = getAll(Config.ES_REPORT_INDEX, Config.ES_REPORT_TYPE, boolQuery,ReportDO.class);
        return result;
    }

    /**
     * 查询所有
     */
    private List getAll(String index, String type, QueryBuilder queryBuilder, Class tClass) throws ExecutionException, InterruptedException {
        SearchResponse searchResponse = buildRequest(index, type, queryBuilder).get();
        String scrollId = searchResponse.getScrollId();
        SearchHits hits = searchResponse.getHits();
        List result = new ArrayList<>();
        addToResult(hits,result,tClass);
        while (true){
            List list = getScrollResult(scrollId, tClass, result);
            if(list == null){
                break;
            }
        }
        return result;

    }
    private  List  getScrollResult(String scrollId,Class tClass, List result) throws ExecutionException, InterruptedException {
        TransportClient client = elasticSearchManager.getClient("ad");
        SearchResponse searchResponse = client.prepareSearchScroll(scrollId)  //设置游标
                .setScroll(TimeValue.timeValueSeconds(ES_SCROLL_TIME))  //设置游标有效期
                .execute()
                .get();
        SearchHits hits = searchResponse.getHits();
        SearchHit[] searchHits = hits.getHits();
        if(searchHits == null || searchHits.length == 0){
            return null;
        }
        addToResult(hits,result,tClass);

        return result;
    }

    private SearchRequestBuilder buildRequest(String index,String type,QueryBuilder queryBuilder) {
        TransportClient client = elasticSearchManager.getClient("ad");
        SearchRequestBuilder builder = client
                .prepareSearch(index)
                .setTypes(type)
                .setScroll(TimeValue.timeValueSeconds(ES_SCROLL_TIME))  //设置游标有效期
                .setSize(pagesize)
                .setQuery(queryBuilder);
        log.info("ElasticsearchDAO query string：\nGET {}/{}/_search\n{} ", index, type, builder.toString());
        return builder;
    }


    private void addToResult(SearchHits hits,List result,Class tClass){
        for (SearchHit hit : hits) {
            String sourceAsString = hit.getSourceAsString();
            Object object = JsonUtil.parseObject(sourceAsString, tClass);
            result.add(object);
        }
    }


}

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