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From "T Jake Luciani (JIRA)" <>
Subject [jira] [Assigned] (CASSANDRA-9619) Read performance regression in tables with many columns on trunk and 2.2 vs. 2.1
Date Wed, 24 Jun 2015 20:52:05 GMT


T Jake Luciani reassigned CASSANDRA-9619:

    Assignee: T Jake Luciani

> Read performance regression in tables with many columns on trunk and 2.2 vs. 2.1
> --------------------------------------------------------------------------------
>                 Key: CASSANDRA-9619
>                 URL:
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Jim Witschey
>            Assignee: T Jake Luciani
>              Labels: perfomance
>             Fix For: 2.2.0 rc2
> There seems to be a regression in read in 2.2 and trunk, as compared to 2.1 and 2.0.
I found it running cstar_perf jobs with 50-column tables. 2.2 may be worse than trunk, though
my results on that aren't consistent. The relevant cstar_perf jobs are here:
> The sequence of commands for these jobs is
> {code}
> stress write n=65000000 -rate threads=300 -col n=FIXED\(50\)
> stress read n=65000000 -rate threads=300
> stress read n=65000000 -rate threads=300
> {code}
> Have a look at the operations per second going from [the first read operation|]
to [the second read operation|].
They've fallen from ~135K to ~100K comparing trunk to 2.1 and 2.0. It's slightly worse for
2.2, and 2.2 operations per second fall continuously from the first to the second read operation.
> There's a corresponding increase in read latency -- it's noticable on trunk and pretty
bad on 2.2. Again, the latency gets higher and higher on 2.2 as the read operations progress
(see the graphs [here|]
and [here|]).
> I see a similar regression in a [more recent test|],
though in this one trunk performed worse than 2.2. This run also didn't display the increasing
latency in 2.2.
> This regression may show for smaller numbers of columns, but not as prominently, as shown
[in the results to this test with the stress default of 5 columns|].
There's an increase in latency variability on trunk and 2.2, but I don't see a regression
in summary statistics.
> My measurements aren't confounded by [the recent regression in cassandra-stress|];
cstar_perf uses the same stress program (from trunk) on all versions on the cluster.
> I'm currently working to
> - reproduce with a smaller workload so this is easier to bisect and debug.
> - get results with larger numbers of columns, since we've seen the regression on 50 columns
but not the stress default of 5.

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