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From Jonathan Haddad <...@jonhaddad.com>
Subject Re: Question on 'Average tombstones per slice' when running cfstats
Date Tue, 07 Jul 2015 00:38:38 GMT
Wouldn't it suggest a delete heavy workload, rather than update?

On Mon, Jul 6, 2015 at 5:21 PM Robert Coli <rcoli@eventbrite.com> wrote:

> On Mon, Jul 6, 2015 at 4:19 PM, Venkatesh Kandaswamy <
> venky@walmartlabs.com> wrote:
>
>>     I cannot find documentation on the last two parameters given by
>> cfstats below. It looks like most examples show 0 for these metrics, but
>> our table has large numbers. What do these mean?
>>
> Average live cells per slice (last five minutes): 2.0
>> Average tombstones per slice (last five minutes): 60.0
>>
>
> They mean what they say they mean?
>
> For each "slice" (which is a weird legacy thriftism you should be able to
> parse as "request" in this context) there was an average of 2 un-masked
> ("live") cells read and 60 cells which were masked ("tombstones").
>
> This is a pretty bad ratio, and suggests that your design does UPDATE-like
> operations, which are not being merged fast enough by compaction to avoid
> you reading past them.
>
> =Rob
>
>
>

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