官方文档提供了这个问题的答案!你可以在这里找到它。

{
  "query": { "match_all": {} },
  "size": 1
}

您只需将size(1)替换为您想要看到的结果的数量!

如果你只是添加一些大的数字作为大小，Elasticsearch会变得非常慢，一种获取所有文档的方法是使用scan和scroll id。

https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-scroll.html

在Elasticsearch v7.2中，您可以这样做:

POST /foo/_search?scroll=1m
{
    "size": 100,
    "query": {
        "match_all": {}
    }
}

这样的结果将包含一个_scroll_id，您必须查询它来获得下一个100块。

POST /_search/scroll 
{
    "scroll" : "1m", 
    "scroll_id" : "<YOUR SCROLL ID>" 
}

调整大小的最佳方法是在URL前面使用size=number

Curl -XGET "http://localhost:9200/logstash-*/_search?size=50&pretty"

注:此尺寸可定义的最大值为10000。对于任何高于10,000的值，它希望您使用滚动函数，这将最大限度地减少对性能的影响。

来自Kibana DevTools的:

GET my_index_name/_search
{
  "query": {
    "match_all": {}
  }
}

这是我使用python客户端发现的最佳解决方案

  # Initialize the scroll
  page = es.search(
  index = 'yourIndex',
  doc_type = 'yourType',
  scroll = '2m',
  search_type = 'scan',
  size = 1000,
  body = {
    # Your query's body
    })
  sid = page['_scroll_id']
  scroll_size = page['hits']['total']

  # Start scrolling
  while (scroll_size > 0):
    print "Scrolling..."
    page = es.scroll(scroll_id = sid, scroll = '2m')
    # Update the scroll ID
    sid = page['_scroll_id']
    # Get the number of results that we returned in the last scroll
    scroll_size = len(page['hits']['hits'])
    print "scroll size: " + str(scroll_size)
    # Do something with the obtained page

https://gist.github.com/drorata/146ce50807d16fd4a6aa

使用java客户端

import static org.elasticsearch.index.query.QueryBuilders.*;

QueryBuilder qb = termQuery("multi", "test");

SearchResponse scrollResp = client.prepareSearch(test)
        .addSort(FieldSortBuilder.DOC_FIELD_NAME, SortOrder.ASC)
        .setScroll(new TimeValue(60000))
        .setQuery(qb)
        .setSize(100).execute().actionGet(); //100 hits per shard will be returned for each scroll
//Scroll until no hits are returned
do {
    for (SearchHit hit : scrollResp.getHits().getHits()) {
        //Handle the hit...
    }

    scrollResp = client.prepareSearchScroll(scrollResp.getScrollId()).setScroll(new TimeValue(60000)).execute().actionGet();
} while(scrollResp.getHits().getHits().length != 0); // Zero hits mark the end of the scroll and the while loop.

https://www.elastic.co/guide/en/elasticsearch/client/java-api/current/java-search-scrolling.html

使用python包elasticsearch-dsl的简单解决方案:

from elasticsearch_dsl import Search
from elasticsearch_dsl import connections

connections.create_connection(hosts=['localhost'])

s = Search(index="foo")
response = s.scan()

count = 0
for hit in response:
    # print(hit.to_dict())  # be careful, it will printout every hit in your index
    count += 1

print(count)

参见https://elasticsearch-dsl.readthedocs.io/en/latest/api.html#elasticsearch_dsl.Search.scan。