APM Server TBS FAQ #2330
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APM Server TBS FAQ #2330
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florent-leborgne
approved these changes
Aug 1, 2025
Co-authored-by: florent-leborgne <[email protected]>
simitt
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Aug 4, 2025
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| :::{dropdown} Why doesn't the sampling rate shown in Storage Explorer match the configured tail sampling rate? | ||
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| In APM Server, the tail sampling policy applied to a distributed trace is determined by evaluating the configured policies in order against the root transaction (the transaction without a parent) and using the first policy that matches. In contrast, the APM UI Storage Explorer calculates the effective average sampling rate for each service using a different method. It considers both head-based and tail-based sampling, but does not account for root transactions. As a result, the sampling rate displayed in Storage Explorer may differ from the configured tail sampling rate, which can give the false impression that tail-based sampling is not functioning correctly. |
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I find this a bit hard to follow. Linking to https://www.elastic.co/docs/solutions/observability/apm/transaction-sampling#distributed-tracing-examples and then building up from there might go a long way.
simitt
approved these changes
Aug 4, 2025
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Add a FAQ section for APM Server Tail based sampling