# 执行命令update-by-query报错"Trying to create too many scroll contexts"
#### 问题现象
云搜索服务的Elasticsearch集群执行命令update-by-query，出现报错"Trying to create too many scroll contexts." ，具体报错信息如下：
```
{"error":{"root_cause":[{"type":"exception","reason":"Trying to create too many scroll contexts. Must be less than or equal to: [100000]. This limit can be set by changing the [search.max_open_scroll_context] setting."},{"type":"exception","reason":"Trying to create too many scroll contexts. Must be less than or equal to: [100000]. ......
```
#### 原因分析
当集群每调用一次scroll的创建接口，都会新建一个scroll使用的context，当scroll contexts的数目达到预定值时，将无法继续创建scroll。
#### 处理步骤
执行如下命令，查看"open_contexts"的参数值即为当前scroll contexts的数目。
```
GET /_nodes/stats/indices/search
```
当数目达到最大值时，可以通过以下两种方式解决。
- 方式一：删除无用的scroll，释放scroll contexts的存储空间。
  ```
  DELETE /_search/scroll
  {
    "scroll_id": "DXF1ZXJ5QW5kRmV0Y2gBAAAAAAAAAD4WYm9laVYtZndUQlNsdDcwakFMNjU1QQ=="
  }
  ```
  
- 方式二：调整"search.max_open_scroll_context"的值，增加scroll contexts的存储空间。
  ```
  PUT /_cluster/settings
  {
    "persistent": {
      "search.max_open_scroll_context": 50000
    },
    "transient": {
      "search.max_open_scroll_context": 50000
    }
  }
  ```
  此数值为示例，请根据实际集群规模设置合理值。