From 5b2f031e8a4c30c171d383c0e44c318b277ca224 Mon Sep 17 00:00:00 2001 From: beorn7 Date: Wed, 8 Oct 2025 16:42:01 +0200 Subject: [PATCH] spec (histograms): Further clarify NHCB federation Signed-off-by: beorn7 --- docs/specs/native_histograms.md | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/docs/specs/native_histograms.md b/docs/specs/native_histograms.md index 0fb13f8c..62ab2323 100644 --- a/docs/specs/native_histograms.md +++ b/docs/specs/native_histograms.md @@ -2371,11 +2371,14 @@ be possible, at least in principle, once native histograms are supported in that format, but federation via protobuf is preferred for efficiency reasons anyway. -NHCBs are rendered as classic histograms when exposed via the federation +TODO: Update once OM supports NH. + +NHCBs are rendered as classic float histograms when exposed via the federation endpoint. Scrapers have the option of converting them back to NHCBs or ingest them as classic histograms. The latter could lead to naming collisions, though. - -TODO: Update once OM supports NH. +Note that OpenMetrics v1 does not support classic float histograms. +Fortunately, Prometheus federation does not use OpenMetrics v1 anyway, but +either the protobuf format or the classic text format. ## OTLP