# Upgrade assistant - how does the reindex helper work?
**URL:** https://discuss.elastic.co/t/upgrade-assistant-how-does-the-reindex-helper-work/152067
**Category:** Elasticsearch
**Created:** [October 11, 2018, 2:06pm UTC](https://discuss.elastic.co/t/upgrade-assistant-how-does-the-reindex-helper-work/152067 "2018-10-11T14:06:04Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@juiip](https://discuss.elastic.co/u/juiip)
#### Post date: [October 11, 2018, 2:06pm UTC](https://discuss.elastic.co/t/upgrade-assistant-how-does-the-reindex-helper-work/152067/1 "2018-10-11T14:06:05Z")
Hi, I am in the process of planning the migration of our current Elasticsearch cluster (version 5.2), to version 6.x.
- Firstly, I was thinking to upgrade to 5.6 in order to have use of Kibana's upgrade assistant. However, it's not entirely clear to me what the upgrade assistant does.
- This [link](https://www.elastic.co/guide/en/kibana/6.0/xpack-upgrade-assistant.html) says there are two functionalities, the first being a cluster checkup and the second being a reindex helper.
- How does the reindex helper work?:
- Where will I define the desired new mapping for each index?
- What happens when the data is loaded into the v6 index mapping structure? - Will it keep the copies of my v5 indices as well? (I don't want v5 indices to be deleted as I have an app that runs search queries against them, this will otherwise break if their structure changes.)
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [November 8, 2018, 2:19pm UTC](https://discuss.elastic.co/t/upgrade-assistant-how-does-the-reindex-helper-work/152067/2 "2018-11-08T14:19:22Z")
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