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I was doing some test on datastax java driver with Eclipse on Mac Pro. Basically, in the eclipse, I was using prepared and batch statement to write (id, name), where id ranges from 10000 to 1000000 and names are student1 - student10000(according to the range of id). After every time I run the code in eclipse, everything goes well, then I use nodetool cfhistograms and proxyhistograms, and cfstats to check the results. However, it seems to be weird. As I was looking forward to see the read latency and write lantency to increase, as I add the range from 10000, 100000, 1000000, 10000000, the final result turns out to be decreasing on the latency.

For example, for the cfhistograms of 10,000 first table and 100,000 second table: Percentile SSTables Write Latency 50% 0 14 75% 0 20 95% 0 42 98% 0 60 99% 0 60 Min 0 5 Max 0 179

and 100,000 below Percentile SSTables Write Latency 50% 0 10 75% 0 12 95% 0 24 98% 0 29 99% 0 42 Min 0 3 Max 0 1109

Also, for the proxyhistogram, 10, 000: Percentile Read Latency Write Latency 50% 1331 72 75% 1916 103 95% 5722 215 98% 5722 310 99% 5722 372 Min 259 30 Max 5722 11864

and 100,000 below: Percentile Read Latency Write Latency 50% 1331 42 75% 1916 50 95% 6866 103 98% 6866 149 99% 6866 215 Min 311 18 Max 6866 61214

Anyone has any idea about this?

Thanks in advance!

Steven

Steven Wu
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  • What is your Topology, Replication Factor & Consistency Level for Write? Are you seeing any activity on Hints table? – Puspendu Banerjee Sep 22 '15 at 20:16
  • @PuspenduBanerjee Actually, I've tested this driver on both amazon aws ec2 and local machine, which use replication factor to be networktopologystrategy(DC1:1, DC2:1) and simplestrategy(rf:1). For the consistency level I did not change anything, so I think it should be 1. For the hints table, where to check it and is there any effect of this? Thanks! – Steven Wu Sep 22 '15 at 23:32
  • select * from system.hints; This will give hints stored for any node – Aravind Chamakura Sep 23 '15 at 04:39
  • @AravindChamakura Thanks for the reply. I got 0 row from the hints:cqlsh:system> select * from hints; target_id | hint_id | message_version | mutation -----------+---------+-----------------+---------- (0 rows) – Steven Wu Sep 23 '15 at 14:54

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