# Create new field in ES and backfill it with data
**URL:** https://discuss.elastic.co/t/create-new-field-in-es-and-backfill-it-with-data/104314
**Category:** Elasticsearch
**Created:** [October 17, 2017, 11:05pm UTC](https://discuss.elastic.co/t/create-new-field-in-es-and-backfill-it-with-data/104314 "2017-10-17T23:05:58Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@Natalia\_Kuleniuk](https://discuss.elastic.co/u/Natalia_Kuleniuk)
#### Post date: [October 17, 2017, 11:05pm UTC](https://discuss.elastic.co/t/create-new-field-in-es-and-backfill-it-with-data/104314/1 "2017-10-17T23:05:58Z")
We have ElasticSearch index that stores large dataset. I need to add two new fields to ES index and backfill values for these fields from Redshift. My question is how can I achieve this? What is the best approach: change existed ES scheme by adding 2 new fields or create new index with all needed fields. I am new to ES, so any suggestions, ideas will be helpful.
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### Author:  [@mujtabahussain](https://discuss.elastic.co/u/mujtabahussain)
#### Post date: [October 17, 2017, 11:24pm UTC](https://discuss.elastic.co/t/create-new-field-in-es-and-backfill-it-with-data/104314/2 "2017-10-17T23:24:20Z")
Lets say you have the two new fields `x` and `y` and each document in the current index had the id `ID`. If you added `x` and `y` to the current index, could you match backfilled values to their relevant ids?
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### Author:  [@Natalia\_Kuleniuk](https://discuss.elastic.co/u/Natalia_Kuleniuk)
#### Post date: [October 17, 2017, 11:41pm UTC](https://discuss.elastic.co/t/create-new-field-in-es-and-backfill-it-with-data/104314/3 "2017-10-17T23:41:09Z")
Yes, I thought I can be able to match them. My ElasticSearch has , for example, 2 fields:"A", "B". I would like to add two more fields "C" and "D".
My Redshift table has fields "A", "C" and "D". So I want to copy fields "C" and "D" from Redshift to ES. Both Redshift and ES have "A" field in common.
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### Author:  [@dadoonet](https://discuss.elastic.co/u/dadoonet)
#### Post date: [October 18, 2017, 6:19am UTC](https://discuss.elastic.co/t/create-new-field-in-es-and-backfill-it-with-data/104314/4 "2017-10-18T06:19:50Z")
You need to reindex. And because you need to reindex all I’d recommend reindexing in a new index.
If you are using aliases which is a good practice, just switch the alias to the new index and drop the old index.
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [November 15, 2017, 3:37pm UTC](https://discuss.elastic.co/t/create-new-field-in-es-and-backfill-it-with-data/104314/6 "2017-11-15T15:37:05Z")
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