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Ben Slater commented on CASSANDRA-12490:
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Hi Benedict,
I must be missing something here because as far as I can tell from testing a
few different scenarios, setting -pop seq=1..N doesn't have any impact on the
set of data generated when used with a YAML file.
That aside, the intent is that you use the SEQ distribution for doing an
initial load of background data before running say a read test or a mixed
read/write test so that you are running with a representative volume of data on
disk (and that you would probably wouldn't use SEQ for these later tests). In
that case you wouldn't expect/care whether the set of data generated initially
lines up in the same order as what is generated by later runs (although you
would expect them to be from the same overall populations of values which I
believe does hold). I believe the sequence of data generation would have to
change similarly if you changed between existing distribution types between
runs?
Looking again at the code, I can see how the current implementation of SEQ is
any issue for implementation future data validation as it doesn't "reset" as
you visit each partition. I think the other distributions effectively rest due
to the call to setSeed(). However, I think this can fairly easily be rectified
by having the setSeed() implementation of DistrubtionSequence reset the next
value to 0?
Cheers
Ben
> Add sequence distribution type to cassandra stress
> --------------------------------------------------
>
> Key: CASSANDRA-12490
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12490
> Project: Cassandra
> Issue Type: Improvement
> Components: Tools
> Reporter: Ben Slater
> Assignee: Ben Slater
> Priority: Minor
> Fix For: 3.10
>
> Attachments: 12490-trunk.patch, 12490.yaml, cqlstress-seq-example.yaml
>
>
> When using the write command, cassandra stress sequentially generates seeds.
> This ensures generated values don't overlap (unless the sequence wraps)
> providing more predictable number of inserted records (and generating a base
> set of data without wasted writes).
> When using a yaml stress spec there is no sequenced distribution available.
> It think it would be useful to have this for doing initial load of data for
> testing
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