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@dkropachev dkropachev commented Sep 12, 2025

When HdrHistogram writes latency if latency is higher than maximum expected it throws error.
Driver catches this error and logs it.
Users get confused since there is no reciepe how to fix it.

Solution is to set advanced.metrics.session.cql-requests.highest-latency to maximum possible latency, which is request timeout.
But since request timeout could be configured on the execution profile, we can't automatically tune highest-latency to match it.
So, only good solution is to give user a hint in the log message.

When HdrHistogram writes latency if latency is higher than maximum
expected it throws error.
Driver catches this error and logs it.
Users get confused since there is no reciepe how to fix it.

Solution is to set advanced.metrics.session.cql-requests.highest-latency
to maximum possible latency, which is request timeout.
But since request timeout could be configured on the execution profile,
we can't automatically tune highest-latency to match it.
So, only good solution is to give user a hint in the log message.
@dkropachev dkropachev self-assigned this Sep 12, 2025
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LGTM

Personally I think this is over the top. reference.conf looks clear enough.

@dkropachev dkropachev merged commit cadd4d4 into scylladb:scylla-4.x Sep 13, 2025
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2 participants