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https://issues.apache.org/jira/browse/CASSANDRA-12744?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16027755#comment-16027755
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Ben Slater commented on CASSANDRA-12744:
----------------------------------------
Actually, I think it's a bit more complex than I just said but still think it's
related to the interaction between the population distribution and the
individual column distributions. Just tried 10,000 inserts with -pop
dist=uniform(1..25) and the following YAML and only get 1 row inserted.
table_definition: |
CREATE TABLE test4 (
pk text,
pk2 text,
val text,
PRIMARY KEY ((pk,pk2))
)
columnspec:
- name: pk
size: fixed(2)
population: exp(1..5)
- name: pk2
size: fixed(2)
population: exp(1..5)
Running with -pop dist=uniform(1..10B) gives the expected 25 rows so it may be
as simple as just setting a really big default population when running in user
mode but I'll do a bit more digging.
> Randomness of stress distributions is not good
> ----------------------------------------------
>
> Key: CASSANDRA-12744
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12744
> Project: Cassandra
> Issue Type: Bug
> Components: Tools
> Reporter: T Jake Luciani
> Assignee: Ben Slater
> Priority: Minor
> Labels: stress
> Fix For: 4.0
>
>
> The randomness of our distributions is pretty bad. We are using the
> JDKRandomGenerator() but in testing of uniform(1..3) we see for 100
> iterations it's only outputting 3. If you bump it to 10k it hits all 3
> values.
> I made a change to just use the default commons math random generator and now
> see all 3 values for n=10
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