Halo,
how to compare the performance level before and after upgrade version?
I don’t know the best way to find out if after upgrade version it decreases or increases.
i need your help 
Hi @bell welcome to the community!
I’m not sure what you mean by this question, but MongoDB strives to ensure that there are no performance degradation with new versions. There is an extensive number of tests in the codebase for this.
There is no “best way” to determine your performance level, if that’s what you’re asking, since this is very use-case specific. Perhaps for typical applications, as long as the database returns data within a set period of time (say, no more than 100ms), then it may be considered to be performant enough. But then, different applications have different ideas of what is acceptable.
But “performance” means many different things, and the optimization of “performance” is a deep topic with many different aspects, such as hardware optimizations, network optimizations, data modelling, schema design, indexing strategies, the nature of the workload, and many, many more.
For starters, you might want to check out this MongoDB.live 2021 talk: 11 Patterns for Extreme MongoDB Performance and Scalability
Best regards
Kevin
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