# Do unique/reusable \_scroll\_ids exist?

**URL:** https://discuss.elastic.co/t/do-unique-reusable--scroll-ids-exist/12280
**Category:** Elasticsearch
**Created:** [June 5, 2013, 3:48pm UTC](https://discuss.elastic.co/t/do-unique-reusable--scroll-ids-exist/12280 "2013-06-05T15:48:43Z")
**Posts on this page:** 1
**Showing post:** 3

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### Author: ![sujoysett](https://avatars.discourse-cdn.com/v4/letter/s/2acd7d/32.png) [@sujoysett](https://discuss.elastic.co/u/sujoysett)
#### Post date: [June 10, 2013, 9:27am UTC](https://discuss.elastic.co/t/do-unique-reusable--scroll-ids-exist/12280/3 "2013-06-10T09:27:31Z")

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Hi,

I had faced this issue quite long ago while implementing custom client side  
code for ES data backup and re-indexing purpose.  
Yes, the scroll ID remains same for few hits, after which it changes.

The solution is to use the scroll ID returned with every hit response in  
the subsequent request, i.e. following an ID chaining mechanism will work.

Using the first scroll ID repeatedly fetches only a few results, not all.  
I guess the scroll ID gets renewed after the timestamp expires (calculated  
from the point of first hit). But this statement is based on random  
observation, I am not sure of this, ES experts can elaborate the underlying  
cause better. I would be glad to know the actual cause too.

- Sujoy.

On Wednesday, June 5, 2013 9:20:34 PM UTC+5:30, Oli wrote:

> Ah, I never gave my example. In case it's of use:
> 
> _Request 1_
> 
> > > curl -XPOST  
> > > 'localhost:9200/foo/bar/\_search?search\_type=scan&scroll=10m&size=10'   
> > > -d  
> > > '{"query":{"constant\_score":{"boost":1,"filter":{"term":{"x":false}}}}}'
> 
> {"\_scroll\_id":"_abc_  
> ","took":1,"timed\_out":false,"\_shards":{"total":5,"successful":5,"failed":0},"hits":{"total":108,"max\_score":0.0,"hits":}}
> 
> _Request 2_
> 
> > > curl -XPOST 'localhost:9200/\_search/scroll?scroll=10m'  
> > > -d '_abc_'
> 
> {"\_scroll\_id":"_abc_","took":1,"timed\_out":false,"\_shards":{"total":5,"successful":5,"failed":0},"hits":{"total":108,"max\_score":0.0,"hits":[{..},  
> {..}]}}
> 
> _.. after some number of requests_
> 
> {"\_scroll\_id":"_def_","took":1,"timed\_out":false,"\_shards":{"total":5,"successful":5,"failed":0},"hits":{"total":108,"max\_score":0.0,"hits":[{..},  
> {..}]}}
> 
> On Wednesday, June 5, 2013 8:48:43 AM UTC-7, Oli wrote:
> 
> > Hi guys,
> > 
> > I'm attempting to implement pagination for our application. The catch is  
> > that our documents require a little post-query filtering, so sometimes if a  
> > user requests 500 documents, we scroll, get 500 from ES, filter and end up  
> > with a lower number. In this case, we perform the next scroll, get a number  
> > of results and build until we have 500 valid docs.
> > 
> > I had some related questions about scrolling / the scroll id returned by  
> > search scroll requests.
> > 
> > _Question1_: Is it possible to use the same scroll id multiple times to  
> > get the same set of results in the over-all result set?
> > 
> > _Question2_: (related to Question1) I'm confused by the scroll\_id  
> > returned whilst doing a scan search then scrolling. What I see is that  
> > that when I start scrolling, for a period of time I get the same \_scroll\_id  
> > back. After some number of requests it changes. I would have expected to  
> > either (1) get the same \_scroll\_id over and over or (2) get a different  
> > \_scroll\_id each time. Are either of these correct? At the bottom of this  
> > mail I've given a short example set of req/resp.
> > 
> > Any pointers on this appreciated. I'd also be interested in hearing from  
> > anyone who has successfully implemented pagination and the approach you  
> > took.
> > 
> > Cheers,  
> > oli

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