#  Problem with fixed\_interval set to 1d for Run downsampling with ILM

**URL:** https://discuss.elastic.co/t/problem-with-fixed-interval-set-to-1d-for-run-downsampling-with-ilm/368417
**Category:** Elasticsearch
**Created:** [October 8, 2024, 8:19am UTC](https://discuss.elastic.co/t/problem-with-fixed-interval-set-to-1d-for-run-downsampling-with-ilm/368417 "2024-10-08T08:19:55Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![wanghuasuzhou](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/wanghuasuzhou/32/138162_2.png) [@wanghuasuzhou](https://discuss.elastic.co/u/wanghuasuzhou)
#### Post date: [October 8, 2024, 8:19am UTC](https://discuss.elastic.co/t/problem-with-fixed-interval-set-to-1d-for-run-downsampling-with-ilm/368417/1 "2024-10-08T08:19:56Z")

</div>

My time zone here is GMT+8, and I encountered a problem running downsampling with ILM: the value in the timestamp @ timestamp field after downsampling has been using the index start\_time (with hours, minutes, and seconds) instead of 00:00:00 UTC time, which makes it impossible for me to use "fixed\_interval": "1d" in the production environment.

However, when I manually called the downsampling interface to test downsampling according to the official documentation (without using IML), the @ timestamp in the downsampled data was 08:00:00.

My question is: If I use ILM, which data will be downsampled and the timestamp field value will use the value on the start\_time index, and when will UTC 00:00:00 be used?

My guess: Due to the GMT+8 time zone I am using here, after sampling, the @ timestamp field value of data before 8 o'clock will use the start\_tme value on the index, while the @ timestamp field value of data after 8 o'clock is 08:00:00. I am not sure if this guess is correct. Does anyone know?