Re: Cassandra seems slow when having many read operations

[Petrus Gomes]

Hi Felipe,

Yes, try it and let us know how it goes.

Thanks,
Petrus Silva.

On Fri, Jul 14, 2017 at 11:37 AM, Felipe Esteves <
felipe.este...@b2wdigital.com> wrote:

> Hi Petrus, thanks for the feedback.
>
> I couldn't found the percent repaired in nodetool info, C* version is
> 2.1.8, maybe it's something newer than that?
>
> I'm analyzing this thread about num_token.
>
> Compaction is "compaction_throughput_mb_per_sec: 16", I don't get pending
> compactions in Opscenter.
>
> One point I've noticed, is that Opscenter show "OS: Disk Latency" max with
> high values when the problem occurs, but it doesn't reflect in server
> directly monitoring, in these tools the IO and latency of disks seems ok.
> But seems to me that "read repair attempted" is a bit high, maybe it will
> explain the latency in reads. I will try to run a repair on cluster to see
> how it goes.
>
> Felipe Esteves
>
> Tecnologia
>
> felipe.este...@b2wdigital.com 
>
> Tel.: (21) 3504-7162 ramal 57162
>
> Skype: felipe2esteves
>
> 2017-07-13 15:02 GMT-03:00 Petrus Gomes :
>
>> How is your Percent Repaired  when you run " nodetool info" ?
>>
>> Search for :
>> "reduced num_token = improved performance ??" topic.
>> The people were discussing that.
>>
>> How is your compaction is configured?
>>
>> Could you run the same process in command line to have a measurement?
>>
>> Thanks,
>> Petrus Silva
>>
>>
>>
>> On Thu, Jul 13, 2017 at 7:49 AM, Felipe Esteves <
>> felipe.este...@b2wdigital.com> wrote:
>>
>>> Hi,
>>>
>>> I have a Cassandra 2.1 cluster running on AWS that receives high read
>>> loads, jumping from 100k requests to 400k requests, for example. Then it
>>> normalizes and later cames another high throughput.
>>>
>>> To the application, it appears that Cassandra is slow. However, cpu and
>>> disk use is ok in every instance, row cache is enabled and with almost 100%
>>> hit rate.
>>>
>>> The logs from Cassandra instances doesn't have any errors, nor tombstone
>>> messages or something liked that. It's mostly compactions and G1GC
>>> operations.
>>>
>>> Any hints on where to investigate more?
>>>
>>>
>>> Felipe Esteves
>>>
>>>
>>>
>>>
>>>
>>
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>
>
>
>

Re: Cassandra table definition with no clustering key

[preetika tyagi]

Hi Michael,

This is exactly what I was looking for. Thank you so much! :)

Preetika

On Fri, Jul 14, 2017 at 8:56 PM, Michael Shuler 
wrote:

> I think this note in the partition key section is what you might be
> looking for?
>
> "Note that a table always has a partition key, and that if the table has
> no clustering columns, then every partition of that table is only
> comprised of a single row (since the primary key uniquely identifies
> rows and the primary key is equal to the partition key if there is no
> clustering columns)."
>
> http://cassandra.apache.org/doc/latest/cql/ddl.html#the-partition-key
>
> --
> Kind regards,
> Michael
>
> On 07/14/2017 06:59 PM, preetika tyagi wrote:
> > Hi all,
> >
> > I'm trying to understand the scenario when no clustering key is
> > specified in a table definition.
> >
> > If a table has only a partition key and no clustering key, what order
> > the rows under the same partition are stored in? Is it even allowed to
> > have multiple rows under the same partition when no clustering key
> > exists? I tried searching for it online but couldn't get a clear
> > explanation.
> >
> > Thanks,
> > Preetika
>
>
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