# Is it possible to Downsamp to a list of keyword values!

**URL:** https://discuss.elastic.co/t/is-it-possible-to-downsamp-to-a-list-of-keyword-values/385393
**Category:** Elasticsearch
**Tags:** ilm-index-lifecycle-management
**Created:** [March 10, 2026, 2:07pm UTC](https://discuss.elastic.co/t/is-it-possible-to-downsamp-to-a-list-of-keyword-values/385393 "2026-03-10T14:07:25Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![A\_Abdellah](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/a_abdellah/32/100734_2.png) [@A\_Abdellah](https://discuss.elastic.co/u/A_Abdellah)
#### Post date: [March 10, 2026, 2:07pm UTC](https://discuss.elastic.co/t/is-it-possible-to-downsamp-to-a-list-of-keyword-values/385393/1 "2026-03-10T14:07:25Z")

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Hello everyone,

I have a time series data stream (TSDS) set up with downsampling configured via ILM (e.g. downsample to 1d intervals daily). The index template is correctly marked with `time_series_dimension`.

My data includes a high-value **keyword** field for example `channel.name` that may changes within each time bucket. Examples: "marketing-campaign-A", "support-ticket-123", etc.

What I would like in the downsampled index For this keyword field have an **aggregation/summary field** that captures the **unique values** that appeared during the downsampling interval.

Ideally something like these in each downsampled document

- `channel_name_unique_values`: ["marketing-A", "support-123"]

Questions:

1. Is there currently (as of early 2026 / latest 8.x or 9.x) any way to achieve unique value aggregation / cardinality on a keyword field **natively during downsampling**?

2. If not, what's the recommended alternative pattern for this use-case?

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<div class="post-metadata">

### Author: ![Rafa\_Silva](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rafa_silva/32/147814_2.png) [@Rafa\_Silva](https://discuss.elastic.co/u/Rafa_Silva)
#### Post date: [March 15, 2026, 3:37am UTC](https://discuss.elastic.co/t/is-it-possible-to-downsamp-to-a-list-of-keyword-values/385393/2 "2026-03-15T03:37:21Z")

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Hi,

At the moment, downsampling for TSDS only supports numeric metric aggregations (min, max, sum, avg, value\_count). It doesn’t support collecting or storing unique values from keyword fields during the downsampling process.

If you need something like a list of unique channel.name values per interval, the usual approach is to pre-aggregate the data before downsampling. This can be done with a transform or an ingest/enrichment pipeline that builds a summarized index where the unique values are stored (for example using a terms aggregation).

Then you can apply downsampling on the numeric metrics while keeping the summarized fields in that intermediate index.