# Global ordinals on high cardinality fields with large indices
**URL:** https://discuss.elastic.co/t/global-ordinals-on-high-cardinality-fields-with-large-indices/229948
**Category:** Elasticsearch
**Created:** [April 27, 2020, 11:48am UTC](https://discuss.elastic.co/t/global-ordinals-on-high-cardinality-fields-with-large-indices/229948 "2020-04-27T11:48:25Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@YvorL](https://discuss.elastic.co/u/YvorL)
#### Post date: [April 27, 2020, 11:48am UTC](https://discuss.elastic.co/t/global-ordinals-on-high-cardinality-fields-with-large-indices/229948/1 "2020-04-27T11:48:25Z")
Hi,
I've got a daily index with a couple of high cardinality fields. Even after reading some threads and the documentation available, I'm not sure how should I proceed. The index has ~600M docs in it every day and the most requested HC field has ~20M unique values. The index has 6 shards on 8 nodes. I'm trying to lower the general memory usage and I'm not sure if adding [eager global ordinals](https://www.elastic.co/guide/en/elasticsearch/reference/master/eager-global-ordinals.html#eager-global-ordinals) to the affected fields' mapping would help in any way or if I change the [execution hint](https://www.elastic.co/guide/en/elasticsearch/reference/master/search-aggregations-bucket-terms-aggregation.html#search-aggregations-bucket-terms-aggregation-execution-hint) to `map` would do any harm. Unfortunately, the queries are aggregating those unique values to different term buckets almost every time.
Any suggestions?
Thanks!
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### Author:  [@Christian\_Dahlqvist](https://discuss.elastic.co/u/Christian_Dahlqvist)
#### Post date: [April 27, 2020, 11:54am UTC](https://discuss.elastic.co/t/global-ordinals-on-high-cardinality-fields-with-large-indices/229948/2 "2020-04-27T11:54:03Z")
If daily indices are no longer written to you can reduce memory usage by forcemerging them down to a single segment as described [in this webinar](https://www.elastic.co/webinars/optimizing-storage-efficiency-in-elasticsearch). It can take a while and result in a lot of disk I/O though.
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### Author:  [@YvorL](https://discuss.elastic.co/u/YvorL)
#### Post date: [April 27, 2020, 11:57am UTC](https://discuss.elastic.co/t/global-ordinals-on-high-cardinality-fields-with-large-indices/229948/3 "2020-04-27T11:57:00Z")
Thank you @Christian_Dahlqvist !
Even if it'd be a segment that's 300GB in size?
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### Author:  [@Christian\_Dahlqvist](https://discuss.elastic.co/u/Christian_Dahlqvist)
#### Post date: [April 27, 2020, 11:57am UTC](https://discuss.elastic.co/t/global-ordinals-on-high-cardinality-fields-with-large-indices/229948/4 "2020-04-27T11:57:38Z")
Is that your shard size??
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### Author:  [@YvorL](https://discuss.elastic.co/u/YvorL)
#### Post date: [April 27, 2020, 11:58am UTC](https://discuss.elastic.co/t/global-ordinals-on-high-cardinality-fields-with-large-indices/229948/5 "2020-04-27T11:58:16Z")
Nope, I have 6 shards so one shard would only be around 50-60GB.
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### Author:  [@Christian\_Dahlqvist](https://discuss.elastic.co/u/Christian_Dahlqvist)
#### Post date: [April 27, 2020, 12:03pm UTC](https://discuss.elastic.co/t/global-ordinals-on-high-cardinality-fields-with-large-indices/229948/6 "2020-04-27T12:03:16Z")
Then will be a segment per shard, but shards that size will take some time to forcemerge.
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### Author:  [@YvorL](https://discuss.elastic.co/u/YvorL)
#### Post date: [April 27, 2020, 12:04pm UTC](https://discuss.elastic.co/t/global-ordinals-on-high-cardinality-fields-with-large-indices/229948/7 "2020-04-27T12:04:50Z")
I see, thanks! I'll watch the webinar soon too. Would eager global ordinals help for the actively written shards?
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### Author:  [@Christian\_Dahlqvist](https://discuss.elastic.co/u/Christian_Dahlqvist)
#### Post date: [April 27, 2020, 12:14pm UTC](https://discuss.elastic.co/t/global-ordinals-on-high-cardinality-fields-with-large-indices/229948/8 "2020-04-27T12:14:33Z")
I do not think so.
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [May 25, 2020, 12:28pm UTC](https://discuss.elastic.co/t/global-ordinals-on-high-cardinality-fields-with-large-indices/229948/9 "2020-05-25T12:28:57Z")
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