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histogram: Find a way of marking a Native Histograms without observations as such #1127

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beorn7 opened this issue Sep 6, 2022 · 2 comments · Fixed by #1314
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histogram: Find a way of marking a Native Histograms without observations as such #1127

beorn7 opened this issue Sep 6, 2022 · 2 comments · Fixed by #1314
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Native Histograms

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beorn7 commented Sep 6, 2022

It is a good thing if the format can expose the conventional and the native version of a histogram side by side. But if a native histogram has a zero threshold of zero and zero observations yet, it might easily look like it’s not a native histogram at all, so Prometheus might ingest it assuming it’s a conventional histogram, which gets weird once it has actually received observations and Prometheus starts to ingest it as a native histogram. See code for details.

This is P2 as explained in the milestone's description.
@beorn7 beorn7 added this to the Native Histograms milestone Sep 6, 2022
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beorn7 commented Oct 11, 2022

How about we require to add a no-op span (length zero) in this case? Those spans are legal, and will be compacted away, but we could use them as the ultimate marker for a native histogram (just for the special case of a histogram without any observations yet and a zero threshold of zero).

Thoughts @codesome @fstab ?

@beorn7 beorn7 self-assigned this Oct 11, 2022
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And empty span seems like the least bad way to do it.

beorn7 added a commit that referenced this issue Jul 20, 2023
@beorn7
histogram: Add a no-op span for an otherwise empty histogram
de4c71a 
Fixes #1127.

If a native histogram has no observations and a zero threshold of
zero, then it is indistinguishable from a classic histogram. To give
scrapers a hint that it is indeed a native histogram, we add a no-op
span.

This needs follow-up PRs in prometheus/prometheus and
prometheus/client_model.

Signed-off-by: beorn7 <beorn@grafana.com>
beorn7 added a commit that referenced this issue Jul 20, 2023
@beorn7
histogram: Add a no-op span for an otherwise empty histogram
3d82c94 
Fixes #1127.

If a native histogram has no observations and a zero threshold of
zero, then it is indistinguishable from a classic histogram. To give
scrapers a hint that it is indeed a native histogram, we add a no-op
span.

This needs follow-up PRs in prometheus/prometheus and
prometheus/client_model.

Signed-off-by: beorn7 <beorn@grafana.com>
beorn7 added a commit to prometheus/client_model that referenced this issue Jul 20, 2023
@beorn7
histogram: Add a doc comment about when to add a no-op span
6f74fd0 
See prometheus/client_golang#1127 for details.

Signed-off-by: beorn7 <beorn@grafana.com>
beorn7 added a commit to prometheus/prometheus that referenced this issue Jul 20, 2023
@beorn7
histogram: Identify native histograms even without observations
4ebf4b3 
Native histograms without observations and with a zero threshold of
zero look the same as classic histograms in the protobuf exposition
format. According to
prometheus/client_golang#1127 , the idea is
to add a no-op span to those histograms to mark them as native
histograms. This commit enables Prometheus to detect that no-op span
and adds a doc comment to the proto spec describing the behavior.

Signed-off-by: beorn7 <beorn@grafana.com>
This was referenced Jul 20, 2023
Merged
Merged
beorn7 added a commit to prometheus/prometheus that referenced this issue Jul 20, 2023
@beorn7
histogram: Identify native histograms even without observations
ef66f6e 
Native histograms without observations and with a zero threshold of
zero look the same as classic histograms in the protobuf exposition
format. According to
prometheus/client_golang#1127 , the idea is
to add a no-op span to those histograms to mark them as native
histograms. This commit enables Prometheus to detect that no-op span
and adds a doc comment to the proto spec describing the behavior.

Signed-off-by: beorn7 <beorn@grafana.com>
@beorn7 beorn7 mentioned this issue Jul 20, 2023
Merged
beorn7 added a commit to prometheus/client_model that referenced this issue Jul 20, 2023
@beorn7
histogram: Add a doc comment about when to add a no-op span
2a367b9 
See prometheus/client_golang#1127 for details.

Signed-off-by: beorn7 <beorn@grafana.com>
beorn7 added a commit to prometheus/prometheus that referenced this issue Jul 20, 2023
@beorn7
histogram: Identify native histograms even without observations
94081a8 
Native histograms without observations and with a zero threshold of
zero look the same as classic histograms in the protobuf exposition
format. According to
prometheus/client_golang#1127 , the idea is
to add a no-op span to those histograms to mark them as native
histograms. This commit enables Prometheus to detect that no-op span
and adds a doc comment to the proto spec describing the behavior.

Signed-off-by: beorn7 <beorn@grafana.com>
beorn7 added a commit to prometheus/prometheus that referenced this issue Jul 26, 2023
@beorn7
histogram: Identify native histograms even without observations
c58e20a 
Native histograms without observations and with a zero threshold of
zero look the same as classic histograms in the protobuf exposition
format. According to
prometheus/client_golang#1127 , the idea is
to add a no-op span to those histograms to mark them as native
histograms. This commit enables Prometheus to detect that no-op span
and adds a doc comment to the proto spec describing the behavior.

Signed-off-by: beorn7 <beorn@grafana.com>
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histogram: Enable detection of a native histogram without observations prometheus/client_golang
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