# Index from another index
**URL:** https://discuss.elastic.co/t/index-from-another-index/14174
**Category:** Elasticsearch
**Created:** [October 30, 2013, 2:00pm UTC](https://discuss.elastic.co/t/index-from-another-index/14174 "2013-10-30T14:00:44Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Uber777](https://discuss.elastic.co/u/Uber777)
#### Post date: [October 30, 2013, 2:00pm UTC](https://discuss.elastic.co/t/index-from-another-index/14174/1 "2013-10-30T14:00:44Z")
So I have a logstash index.
How do I extract (regex) key values like Error type, date and time for
their own elastic search index from an existing index?
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### Author:  [@spinscale](https://discuss.elastic.co/u/spinscale)
#### Post date: [October 31, 2013, 10:29am UTC](https://discuss.elastic.co/t/index-from-another-index/14174/2 "2013-10-31T10:29:16Z")
Hey,
your requirement basically means, that you have to retrieve every document
from your index, modify it (in your case remove some fields except three)
and then reindex your document. I am not sure, if there is some automatic
tool for this, but it only requires two manual steps, so it is quite simple
to do it yourself
You can use the scroll query for this, see
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While you are getting back the results, you could use a
python/ruby/whateveryoulike script to do the actuall modifications and
execute the index operation in another index (preferrably batched).
Hope this helps
--Alex
On Wed, Oct 30, 2013 at 3:00 PM, Uber777 [nkatsikanis@gmail.com](mailto:nkatsikanis@gmail.com) wrote:
> So I have a logstash index.
>
> How do I extract (regex) key values like Error type, date and time for
> their own Elasticsearch index from an existing index?
>
> --
> You received this message because you are subscribed to the Google Groups
> "elasticsearch" group.
> To unsubscribe from this group and stop receiving emails from it, send an
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 6, 2017, 2:09am UTC](https://discuss.elastic.co/t/index-from-another-index/14174/3 "2017-07-06T02:09:39Z")