From d87414c57c05c4635d7b082aad2ebc4d0d7a3b8e Mon Sep 17 00:00:00 2001 From: Aliaksandr Valialkin Date: Mon, 20 Dec 2021 12:30:09 +0200 Subject: [PATCH] docs/FAQ.md: describe main reasons for high churn rate --- docs/FAQ.md | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/docs/FAQ.md b/docs/FAQ.md index 30873e46e5..d7b63115b3 100644 --- a/docs/FAQ.md +++ b/docs/FAQ.md @@ -282,6 +282,13 @@ If old time series are constantly substituted by new time series at a high rate, * Increased size of inverted index, which is stored at `<-storageDataPath>/indexdb`, since the inverted index contains entries for every label of every time series with at least a single ingested sample * Slow down of queries over multiple days. +The main reason for high churn rate is a metric label with frequently changed value. Examples of such labels: + +* `queryid`, which changes with each query at `postgres_exporter`. +* `app_name` or `deployment_id`, which changes with each new deployment in Kubernetes. +* A label derived from the current time such as `timestamp`, `minute` or `hour`. +* A `hash` or `uuid` label, which changes frequently. + The solution against high churn rate is to identify and eliminate labels with frequently changed values. The [/api/v1/status/tsdb](https://docs.victoriametrics.com/#tsdb-stats) page can help determining these labels.