# Different behaviour from 7.6.2 and 7.8.1

**URL:** <https://discuss.elastic.co/t/different-behaviour-from-7-6-2-and-7-8-1/245245>\
**Category:** Elasticsearch\
**Tags:** transforms\
**Created:** [August 17, 2020, 2:03pm UTC](https://discuss.elastic.co/t/different-behaviour-from-7-6-2-and-7-8-1/245245 "2020-08-17T14:03:05Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![DavidKHE](https://avatars.discourse-cdn.com/v4/letter/d/47e85d/32.png) [@DavidKHE](https://discuss.elastic.co/u/DavidKHE)\
**Post date:** [August 17, 2020, 2:03pm UTC](https://discuss.elastic.co/t/different-behaviour-from-7-6-2-and-7-8-1/245245/1 "2020-08-17T14:03:06Z")

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Hi,

use case - merging two indexes into new output.  
the flow is to take 2 indexes, both having timestamp and pivot by time where aggregations are unique to each index. KPI1 - index1 and KPI2 - index2.

when using ES 7.6.1 as long as the pivot keys are same no issues.  
when using ES 7.8.1 this actually no longer works the same transformation. as workaround we found that both indexes have to identical from mapping perspective on the aggregations fields. otherwise it will not work.

basically the main issue is that this is not smooth upgrade if you have running transformations with merging indexes.

my kind suggestion is to bring back the previous functionality as in 7.6.1

Best Regards,  
David

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**Author:** ![sophie\_chang](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/sophie_chang/32/18008_2.png) [@sophie\_chang](https://discuss.elastic.co/u/sophie_chang)\
**Post date:** [August 17, 2020, 3:51pm UTC](https://discuss.elastic.co/t/different-behaviour-from-7-6-2-and-7-8-1/245245/2 "2020-08-17T15:51:05Z")

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@DavidKHE Would it be possible to share the transform configs and a sample doc from each index so we can replicate?

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [September 14, 2020, 3:51pm UTC](https://discuss.elastic.co/t/different-behaviour-from-7-6-2-and-7-8-1/245245/3 "2020-09-14T15:51:15Z")

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Closed on September 14, 2020, 3:51pm UTC

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