# Elasticsearch7.x have serious performance problems

**URL:** <https://discuss.elastic.co/t/elasticsearch7-x-have-serious-performance-problems/261362>\
**Category:** Elasticsearch\
**Tags:** es-hadoop\
**Created:** [January 18, 2021, 12:37am UTC](https://discuss.elastic.co/t/elasticsearch7-x-have-serious-performance-problems/261362 "2021-01-18T00:37:18Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![gaocx2000cn](https://avatars.discourse-cdn.com/v4/letter/g/c5a1d2/32.png) [@gaocx2000cn](https://discuss.elastic.co/u/gaocx2000cn)\
**Post date:** [January 18, 2021, 12:37am UTC](https://discuss.elastic.co/t/elasticsearch7-x-have-serious-performance-problems/261362/1 "2021-01-18T00:37:18Z")

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Elasticsearch7.x have serious performance problems.  
We have a indexes set which have total 3800M doc, 5000G bytes.  
**1. Searching performance**  
We run a lot of queries against Elasticsearch6.2.1 and Elasticsearch7.9.2 cluster.  
The average took time on Elasticsearch6.2.1 is \_TOOK\_AVG62.  
The average took time on Elasticsearch7.9.2 is \_TOOK\_AVG79.  
\_TOOK\_AVG79 / \_TOOK\_AVG62 = 2.6  
Same query takes longer on Elasticsearch7.9.2.

**2. Focemerging performance**  
Our test cluster is 20 data nodes, 190 primary shards, 1 replica.  
When we run the focemerge on the ElasticSearch6.2.1 cluster with max\_num\_segments=1, it will take 5.5 hours.  
When we run the focemerge on the ElasticSearch7.9.2 cluster with max\_num\_segments=1, it will take 17.5 hours.

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**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\
**Post date:** [January 18, 2021, 12:41am UTC](https://discuss.elastic.co/t/elasticsearch7-x-have-serious-performance-problems/261362/2 "2021-01-18T00:41:26Z")

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A 5TB index is pretty large. What sort of data is this?

> [@gaocx2000cn](#):
>
> The average took time on Elasticsearch6.2.1 is \_TOOK\_AVG62.  
> The average took time on Elasticsearch7.9.2 is \_TOOK\_AVG79.

That's 17 milliseconds difference though. I understand it's larger, but that's still pretty small.

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**Author:** ![gaocx2000cn](https://avatars.discourse-cdn.com/v4/letter/g/c5a1d2/32.png) [@gaocx2000cn](https://discuss.elastic.co/u/gaocx2000cn)\
**Post date:** [January 18, 2021, 12:47am UTC](https://discuss.elastic.co/t/elasticsearch7-x-have-serious-performance-problems/261362/3 "2021-01-18T00:47:05Z")

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They are user shopping data.

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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:** [February 15, 2021, 12:47am UTC](https://discuss.elastic.co/t/elasticsearch7-x-have-serious-performance-problems/261362/4 "2021-02-15T00:47:21Z")

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