Elasticsearch Scroll



Elasticsearch Scroll

Opster Team

July 2020, Version: 1.7-8.0


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Scroll in Elasticsearch

What it is

In Elasticsearch, the concept of scroll comes into play when you have a large set of search results. Large search results are exhaustive for both the Elasticsearch cluster and the requesting client in terms of memory and processing. The scroll API enables you  to take a snapshot of a large number of results from a single search request.

Examples

To perform a scroll search, you need to add the scroll parameter to search query and specify how long Elasticsearch should keep the search context viable.

GET mydocs-2019/_search?scroll=40s
{
"size": 5000,
"query": {
"match_all": {}
},
"sort": [
 {
 "_doc": {
  "order": "asc"
   }
  }
 ]
}

This query will return a maximum of  5000 hits and if the scroll is idle for more than 40  seconds, then it will be deleted. The response will return the first page of the results and a scroll id, you can use the scroll id to get additional documents from the scroll. You’re able to keep retrieving the documents until you have all of them.

Notes
  • Changes made to documents after the scroll will not show up in your results.
  • When you are done with the scroll, you can delete it manually using the scroll id.
DELETE _search/scroll/<sroll_id>

Related log errors to this ES concept


Clear SC failed on node
Failed to clear scroll
OnNewScrollContext listener failed
OnFreeScrollContext listener failed
Giving up on search because it failed with a non-retryable exception
Failed to clear scroll
Scroll request failed; scrolling document(s) is stopped
Unable to clear scroll id :
Unable to execute scroll request
Failed to send error response for action clear_sc and request

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