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Posted to user@cassandra.apache.org by Rene Kochen <re...@schange.com> on 2013/09/19 11:31:04 UTC
Row size in cfstats vs cfhistograms
Hi all,
I use Cassandra 1.0.11
If I do cfstats for a particular column family, I see a "Compacted row
maximum size" of 43388628
However, when I do a cfhistograms I do not see such a big row in the Row
Size column. The biggest row there is 126934.
Can someone explain this?
Thanks!
Rene
Re: Row size in cfstats vs cfhistograms
Posted by Rene Kochen <re...@emea.schange.com>.
That is indeed how I read it. The maximal size is 3 rows with an offset of
126934, while cfstats reports 43388628.
Thanks,
Rene
2013/9/19 Richard Low <ri...@wentnet.com>
> On 19 September 2013 10:31, Rene Kochen <re...@schange.com> wrote:
>
> I use Cassandra 1.0.11
>>
>> If I do cfstats for a particular column family, I see a "Compacted row
>> maximum size" of 43388628
>>
>> However, when I do a cfhistograms I do not see such a big row in the Row
>> Size column. The biggest row there is 126934.
>>
>> Can someone explain this?
>>
>
> The 'Row Size' column is showing the number of rows that have a size
> indicated by the value in the 'Offset' column. So if your output is like
>
> Offset Row Size
> 1131752 10
> 1358102 100
>
> It means you have 100 rows with size between 1131752 and 1358102 bytes.
> It doesn't mean there are rows of size 100.
>
> Richard.
>
Re: Row size in cfstats vs cfhistograms
Posted by Richard Low <ri...@wentnet.com>.
On 19 September 2013 10:31, Rene Kochen <re...@schange.com> wrote:
I use Cassandra 1.0.11
>
> If I do cfstats for a particular column family, I see a "Compacted row
> maximum size" of 43388628
>
> However, when I do a cfhistograms I do not see such a big row in the Row
> Size column. The biggest row there is 126934.
>
> Can someone explain this?
>
The 'Row Size' column is showing the number of rows that have a size
indicated by the value in the 'Offset' column. So if your output is like
Offset Row Size
1131752 10
1358102 100
It means you have 100 rows with size between 1131752 and 1358102 bytes. It
doesn't mean there are rows of size 100.
Richard.
Re: Row size in cfstats vs cfhistograms
Posted by Rene Kochen <re...@emea.schange.com>.
Nice! Thats explains it.
2013/9/19 Robert Coli <rc...@eventbrite.com>
> On Thu, Sep 19, 2013 at 3:08 AM, Rene Kochen <re...@schange.com>wrote:
>
>> And how does cfstats track the maximum size? What does "Compacted" mean
>> in "Compacted row maximum size".
>>
>
> That maximum size is "the largest row that I have encountered in the
> course of compaction, since I started."
>
> Hence "compacted," to try to indicate that it is not necessarily the row
> of maximum size which currently exists. For example, if you had a huge row
> at some time in the past and have now removed it (and have not restarted in
> the interim) this value will be misleading.
>
> =Rob
>
Re: Row size in cfstats vs cfhistograms
Posted by Robert Coli <rc...@eventbrite.com>.
On Thu, Sep 19, 2013 at 3:08 AM, Rene Kochen <re...@schange.com>wrote:
> And how does cfstats track the maximum size? What does "Compacted" mean in
> "Compacted row maximum size".
>
That maximum size is "the largest row that I have encountered in the course
of compaction, since I started."
Hence "compacted," to try to indicate that it is not necessarily the row of
maximum size which currently exists. For example, if you had a huge row at
some time in the past and have now removed it (and have not restarted in
the interim) this value will be misleading.
=Rob
Re: Row size in cfstats vs cfhistograms
Posted by Rene Kochen <re...@schange.com>.
And how does cfstats track the maximum size? What does "Compacted" mean in
"Compacted row maximum size".
Thanks again!
Rene
2013/9/19 Michał Michalski <mi...@opera.com>
> I believe the reason is that cfhistograms tells you about the sizes of the
> rows returned by given node in a response to the read request, while
> cfstats tracks the largest row stored on given node.
>
> M.
>
> W dniu 19.09.2013 11:31, Rene Kochen pisze:
>
> Hi all,
>>
>> I use Cassandra 1.0.11
>>
>> If I do cfstats for a particular column family, I see a "Compacted row
>> maximum size" of 43388628
>>
>> However, when I do a cfhistograms I do not see such a big row in the Row
>> Size column. The biggest row there is 126934.
>>
>> Can someone explain this?
>>
>> Thanks!
>>
>> Rene
>>
>>
>
Re: Row size in cfstats vs cfhistograms
Posted by Michał Michalski <mi...@opera.com>.
I believe the reason is that cfhistograms tells you about the sizes of
the rows returned by given node in a response to the read request, while
cfstats tracks the largest row stored on given node.
M.
W dniu 19.09.2013 11:31, Rene Kochen pisze:
> Hi all,
>
> I use Cassandra 1.0.11
>
> If I do cfstats for a particular column family, I see a "Compacted row
> maximum size" of 43388628
>
> However, when I do a cfhistograms I do not see such a big row in the Row
> Size column. The biggest row there is 126934.
>
> Can someone explain this?
>
> Thanks!
>
> Rene
>