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Posted to dev@cassandra.apache.org by graham sanderson <gr...@vast.com> on 2013/12/13 02:00:15 UTC

Issue with SizeTieredCompactionStrategy in 2.0.3

I just created https://issues.apache.org/jira/browse/CASSANDRA-6483 for an issue introduced it seems by https://issues.apache.org/jira/browse/CASSANDRA-6109

Note that the latter feature claims to be “off” by default, however it isn’t immediately clear to me from the patch how that “off” is implemented, and whether it is supposed to go down that code path even when “off"

I’d be interested if anyone can shed some light on that, I’m happy to fix the issue (but would love to “turn it off” in the interim as it spams our ERROR monitoring - I’m guessing there is no other actual downside, since it just fails a subset of compaction runs

Thanks,

Graham.

Re: Issue with SizeTieredCompactionStrategy in 2.0.3

Posted by graham sanderson <gr...@vast.com>.

Thanks Tyler

I guess I was looking at the original patch which had
protected static final double DEFAULT_MAX_COLD_READS_RATIO = 0.025;

On Dec 13, 2013, at 9:53 AM, Tyler Hobbs <ty...@datastax.com> wrote:

> Hi Graham, thanks for reporting this.  I should be able to get it fixed
> shortly.
> 
> As far as how it's off by default, the default max_cold_reads_ratio is 0.0,
> so filterColdSSTables() won't actually filter anything.  I can add a check
> to skip that function if maxColdReadsRatio is 0.0 in the 6483 patch.
> 
> 
> On Thu, Dec 12, 2013 at 7:00 PM, graham sanderson <gr...@vast.com> wrote:
> 
>> I just created https://issues.apache.org/jira/browse/CASSANDRA-6483 for
>> an issue introduced it seems by
>> https://issues.apache.org/jira/browse/CASSANDRA-6109
>> 
>> Note that the latter feature claims to be “off” by default, however it
>> isn’t immediately clear to me from the patch how that “off” is implemented,
>> and whether it is supposed to go down that code path even when “off"
>> 
>> I’d be interested if anyone can shed some light on that, I’m happy to fix
>> the issue (but would love to “turn it off” in the interim as it spams our
>> ERROR monitoring - I’m guessing there is no other actual downside, since it
>> just fails a subset of compaction runs
>> 
>> Thanks,
>> 
>> Graham.
>> 
> 
> 
> 
> -- 
> Tyler Hobbs
> DataStax <http://datastax.com/>

Re: Issue with SizeTieredCompactionStrategy in 2.0.3

Posted by Tyler Hobbs <ty...@datastax.com>.

Hi Graham, thanks for reporting this.  I should be able to get it fixed
shortly.

As far as how it's off by default, the default max_cold_reads_ratio is 0.0,
so filterColdSSTables() won't actually filter anything.  I can add a check
to skip that function if maxColdReadsRatio is 0.0 in the 6483 patch.

On Thu, Dec 12, 2013 at 7:00 PM, graham sanderson <gr...@vast.com> wrote:

> I just created https://issues.apache.org/jira/browse/CASSANDRA-6483 for
> an issue introduced it seems by
> https://issues.apache.org/jira/browse/CASSANDRA-6109
>
> Note that the latter feature claims to be “off” by default, however it
> isn’t immediately clear to me from the patch how that “off” is implemented,
> and whether it is supposed to go down that code path even when “off"
>
> I’d be interested if anyone can shed some light on that, I’m happy to fix
> the issue (but would love to “turn it off” in the interim as it spams our
> ERROR monitoring - I’m guessing there is no other actual downside, since it
> just fails a subset of compaction runs
>
> Thanks,
>
> Graham.
>

-- 
Tyler Hobbs
DataStax <http://datastax.com/>