Re: Cassandra p95 latencies

[Jeff Jirsa]

You’re going to have to help us help you  4.0 is pretty widely deployed. I’m not aware of a perf regression  Can you give us a schema (anonymized) and queries and show us a trace ?  On Aug 10, 2023, at 10:18 PM, Shaurya Gupta <shaurya.n...@gmail.com> wrote:  The queries are rightly designed as I already explained. 40 ms is way too high as compared to what I seen with other DBs and many a times with Cassandra 3.x versions. CPU consumed as I mentioned is not high, it is around 20%. On Thu, Aug 10, 2023 at 5:14 PM MyWorld <timeplus.1...@gmail.com> wrote: Hi, P95 should not be a problem if rightly designed. Levelled compaction strategy further reduces this, however it consume some resources. For read, caching is also helpful.  Can you check your cpu iowait as it could be the reason for delay  Regards, Ashish On Fri, 11 Aug, 2023, 04:58 Shaurya Gupta, <shaurya.n...@gmail.com> wrote: Hi community What is the expected P95 latency for Cassandra Read and Write queries executed with Local_Quorum over a table with 3 replicas ? The queries are done using the partition + clustering key and row size in bytes is not too much, maybe 1-2 KB maximum. Assuming CPU is not a crunch ? We observe those to be 40 ms P95 Reads and same for Writes. This looks very high as compared to what we expected. We are using Cassandra 4.0. Any documentation / numbers will be helpful. Thanks -- Shaurya Gupta -- Shaurya Gupta