From c8f76e3408932a89a9eb1f32eab784f2974dc4bb Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Giedrius=20Statkevi=C4=8Dius?= Date: Thu, 25 Jun 2020 19:41:24 +0300 Subject: [PATCH] docs: compact: add blurb about how retention policy works MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add some verbiage that explains when exactly do the blocks get deleted. Closes #2782. Signed-off-by: Giedrius Statkevičius --- docs/components/compact.md | 2 ++ 1 file changed, 2 insertions(+) diff --git a/docs/components/compact.md b/docs/components/compact.md index 1ca48e14a8..99f5e6a30c 100644 --- a/docs/components/compact.md +++ b/docs/components/compact.md @@ -49,6 +49,8 @@ Ideally, you will have equal retention set (or no retention at all) to all resol Not setting this flag, or setting it to `0d`, i.e. `--retention.resolution-X=0d`, will mean that samples at the `X` resolution level will be kept forever. +Please note that blocks are only deleted after they completely "fall off" of the specified retention policy. In other words, the "max time" of a block needs to be older than the amount of time you had specified. + ## Storage space consumption In fact, downsampling doesn't save you any space but instead it adds 2 more blocks for each raw block which are only slightly smaller or relatively similar size to raw block. This is required by internal downsampling implementation which to be mathematically correct holds various aggregations. This means that downsampling can increase the size of your storage a bit (~3x), but it gives massive advantage on querying long ranges.