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From Ahmed Eljami <ahmed.elj...@gmail.com>
Subject Re: Cassandra copy command
Date Thu, 22 Aug 2019 09:04:00 GMT
Hello,

As Jean said il will be preferable to use  http://cassandra-reaper.io

So you don't have to manually manage the consistency of your cassandra ring
nor the list of nodes to repair.


Le mer. 21 août 2019 à 15:57, Rahul Reddy <rahulreddy1234@gmail.com> a
écrit :

> Thanks Jean,
>
> I have dc1 and dc2 existing. added dc3 from dc1 and dc4 from dc2. If I
> want to run repair on one node in dc3 from dc1 only is it possible?
>
> On Wed, Aug 21, 2019, 8:11 AM Jean Carlo <jean.jeancarl48@gmail.com>
> wrote:
>
>> Hello Rahul,
>>
>> To ensure the consistency among the DCs, it is enough to run a repair
>> command.
>>
>> You can do it using http://cassandra-reaper.io/
>> or runing the commande *nodetool repair* with the respectively options
>> in every node.
>>
>> You do not need to count the rows in every DC to ensure cassandra is sync
>> amongs DC after you have run the repair. But if you still want to do it,
>> use Spark for it.
>>
>> Jean Carlo
>>
>> "The best way to predict the future is to invent it" Alan Kay
>>
>>
>> On Wed, Aug 21, 2019 at 1:51 PM Rahul Reddy <rahulreddy1234@gmail.com>
>> wrote:
>>
>>> Yep I did run rebuild   on each new node
>>>
>>> On Wed, Aug 21, 2019, 7:25 AM Stefan Miklosovic <
>>> stefan.miklosovic@instaclustr.com> wrote:
>>>
>>>> Hi Rahul,
>>>>
>>>> how did you add that dc3 to cluster? The rule of thumb here is to do
>>>> rebuild from each node, for example like here
>>>>
>>>> https://docs.datastax.com/en/archived/cassandra/3.0/cassandra/operations/opsAddDCToCluster.html
>>>>
>>>> On Wed, 21 Aug 2019 at 12:57, Rahul Reddy <rahulreddy1234@gmail.com>
>>>> wrote:
>>>> >
>>>> > Hi sefan,
>>>> >
>>>> > I'm adding new DC3 to exiting cluster and see discripencies couple of
>>>> millions in Nodetool cfstats in new DC.
>>>> >
>>>> > My table size is 50gb
>>>> > I'm trying to run copy entire table.
>>>> >
>>>> > Copy table to 'full_tablr.csv' with delimiter ',';
>>>> >
>>>> > If I run above command from dc3. Does it get the data only from dc3?
>>>> >
>>>> >
>>>> >
>>>> > On Wed, Aug 21, 2019, 6:46 AM Stefan Miklosovic <
>>>> stefan.miklosovic@instaclustr.com> wrote:
>>>> >>
>>>> >> Hi Rahul,
>>>> >>
>>>> >> what is your motivation behind this? Why do you want to make sure
the
>>>> >> count is same? What is the purpose of that? All you should care
about
>>>> >> is that Cassandra will return you right results. It was designed
from
>>>> >> the very bottom to do that for you, you should not be bothered too
>>>> >> much about such discrepancies, they will be always there in general.
>>>> >> But the important fact is that once queried, you can rest assured
it
>>>> >> is returned (and consequentially repaired if data not match) as
they
>>>> >> should.
>>>> >>
>>>> >> What copy command you are talking about precisely, why you cant
use
>>>> just repair?
>>>> >>
>>>> >> On Wed, 21 Aug 2019 at 12:14, Rahul Reddy <rahulreddy1234@gmail.com>
>>>> wrote:
>>>> >> >
>>>> >> > Hello,
>>>> >> >
>>>> >> > I have 3 datacenters . Want to make sure record count is same
in
>>>> all dc's . If I run copy command node1 in dc1 does it get the data from
>>>> only dc1? Nodetool cfstats I'm seeing discrepancies in partitions count is
>>>> it because we didn't run cleanup after adding few nodes and remove them?.
>>>> To rule out any discripencies I want to run copy command from 3 DC's and
>>>> compare. Please let me know if copy command extracts data from the DC only
>>>> I ran it from?
>>>> >>
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>>>> >>
>>>>
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>>>>
>>>>

-- 
Cordialement;

Ahmed ELJAMI

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