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https://issues.apache.org/jira/browse/CASSANDRA-7731?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14133997#comment-14133997
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Cyril Scetbon edited comment on CASSANDRA-7731 at 9/15/14 4:12 PM:
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bq. the weighted one is the default but you can specify it to length of
application
what do you mean ? we don't want to change it to be the maximum value since the
application started. The only matter concerns the fact that in some cases it's
not the maximum for the last 5 minutes but can be for the last 20 minutes like
in my case. Do you think, the last version of metrics could enforce it to
corresponds to the last 5 minutes ? AFAIU the documentation it says that as
[exponentially decaying reservoirs|
https://dropwizard.github.io/metrics/2.2.0/manual/core/#biased-histograms] use
a forward-decaying priority reservoir it should represent the recent data
was (Author: cscetbon):
bq. the weighted one is the default but you can specify it to length of
application
what do you mean ? we don't want to change it to be the maximum value since the
application started. The only matter concerns the fact that in some cases it's
not the maximum for the last 5 minutes but can be for the last 20 minutes like
in my case. Do you think, the last version of metrics could enforce it to
corresponds to the last 5 minutes ? AFAIU the documentation it says that as
[exponentially decaying reservoirs|
https://dropwizard.github.io/metrics/3.1.0/manual/core/#exponentially-decaying-reservoirs]
use a forward-decaying priority reservoir it should represent the recent data
> Get max values for live/tombstone cells per slice
> -------------------------------------------------
>
> Key: CASSANDRA-7731
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7731
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Cyril Scetbon
> Assignee: Robert Stupp
> Priority: Minor
> Fix For: 2.1.1
>
> Attachments: 7731-2.0.txt, 7731-2.1.txt
>
>
> I think you should not say that slice statistics are valid for the [last five
> minutes
> |https://github.com/apache/cassandra/blob/cassandra-2.0/src/java/org/apache/cassandra/tools/NodeCmd.java#L955-L956]
> in CFSTATS command of nodetool. I've read the documentation from yammer for
> Histograms and there is no way to force values to expire after x minutes
> except by
> [clearing|http://grepcode.com/file/repo1.maven.org/maven2/com.yammer.metrics/metrics-core/2.1.2/com/yammer/metrics/core/Histogram.java#96]
> it . The only thing I can see is that the last snapshot used to provide the
> median (or whatever you'd used instead) value is based on 1028 values.
> I think we should also be able to detect that some requests are accessing a
> lot of live/tombstone cells per query and that's not possible for now without
> activating DEBUG for SliceQueryFilter for example and by tweaking the
> threshold. Currently as nodetool cfstats returns the median if a low part of
> the queries are scanning a lot of live/tombstone cells we miss it !
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