HammerDB v6.0 响应时间、百分位和蓄水池采样
HammerDB v6.0 Response Times, Percentiles and Reservoir Sampling

原始链接: https://www.hammerdb.com/blog/uncategorized/hammerdb-v6-0-response-times-percentiles-and-reservoir-sampling/

数据库基准测试往往优先考虑吞吐量而非延迟,这导致了一个常见错误,即过度增加工作负载,直到响应时间下降到数百毫秒。对于关键任务数据库而言,真正的性能应保持在亚毫秒或低毫秒级范围内。 HammerDB v6.0 通过将重点从容易掩盖瓶颈的简单平均值转向详细的延迟分析,解决了这一问题。此次更新提供了完整的百分位报告和交易类型的箱线图,使用户能够识别中位数性能、离散度和异常值。这确保了用户能够区分持续的低延迟和因排队导致的工作负载延迟。 此外,HammerDB v6.0 引入了蓄水池采样(reservoir sampling),使得在长时间运行的测试中进行实用的响应时间分析成为可能,且不会产生数据处理瓶颈。通过捕获吞吐量和延迟分布,该工具可帮助管理员准确识别系统从峰值性能过渡到过载状态的临界点。简而言之,HammerDB v6.0 确保了基准测试能够揭示完整的性能状况,证明如果高吞吐量是以不可接受的响应时间为代价,那么它将毫无意义。

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原文

One of the biggest mistakes in database benchmarking is oversizing the workload until response times are measured in hundreds of milliseconds, or even seconds.

A large throughput number is not enough if the workload is already spending too long waiting. The result may look impressive at the top level, but the response times tell a different story.

The databases supported by HammerDB are all mission-critical, enterprise-class databases. At high performance, response times should be in the sub-millisecond or low millisecond range for complex stored procedures combining multiple SQL statements.

HammerDB v6.0 makes the latency profile visible.

The new response time metrics show how long individual transactions take across the run, with full percentile reporting and box plots for the key transaction types.

That means the result can show the median, higher percentiles, spread and outliers, not just an average. Averages hide too much. Percentiles show whether the system is delivering consistent low latency or whether part of the workload is already queueing behind longer waits.

HammerDB v6.0 also adds reservoir sampling for long runs. This keeps response time analysis practical even when a workload generates a very large number of transaction timings.

For long-running tests, that is important. You want the latency distribution, percentiles and outliers without turning the response time data itself into a bottleneck.

As virtual users increase, throughput and response time should be reviewed together. If throughput rises but latency moves from milliseconds to hundreds of milliseconds, the workload has crossed into overload.

HammerDB v6.0 makes that easier to see.

Run the workload. Capture the throughput. Check the percentiles. Review the response time distribution.

HammerDB v6.0 makes database benchmarking show latency as well as throughput.

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