Discussion:
Test of datastax java driver on cassandra and using nodetool
Jun Wu
2015-09-23 00:37:10 UTC
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Dear All,



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

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