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Preserve reset hint during histogram deduplication #7092

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Preserve reset hint during histogram deduplication #7092

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Commits on Feb 23, 2024

  1. Preserve reset hint during histogram deduplication 

    Penalty based deduplication can over-skip samples because when switching
between replicas, because it uses a penalty of 2 times the estimated scrape interval.
This works okay for float counters because the reset is detected based on the value of the counter.
With native histograms, detecting a reset is much more expensive which is why there is a
hint stored in the first sample of a chunk, which indicates whether the chunk has been created
because of a reset.

It can easily happen that the dedup iterator switches replicas, and skips the first sample of a chunk
because of the added penalty. In this case we will not read the hint and will assume that no
histogram reset happened.

This commit fixes the issue by explicitly calling DetectReset if a replica stream has been switched.
The result is then stored and set in the histogram returned by AtHistogram and AtFloatHistogram.

Signed-off-by: Filip Petkovski <filip.petkovsky@gmail.com>
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    fpetkovski committed Feb 23, 2024
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  2. Add unit test 

    Signed-off-by: Filip Petkovski <filip.petkovsky@gmail.com>
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    fpetkovski committed Feb 23, 2024
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  3. Fix lint 

    Signed-off-by: Filip Petkovski <filip.petkovsky@gmail.com>
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    fpetkovski committed Feb 23, 2024
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