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From Joost Ouwerkerk <jo...@openplaces.org>
Subject Re: Cassandra reverting deletes?
Date Wed, 28 Apr 2010 20:56:29 GMT
Yes! Reproduced on single-node cluster:

10/04/28 16:30:24 INFO mapred.JobClient:     ROWS=274884
10/04/28 16:30:24 INFO mapred.JobClient:     TOMBSTONES=951083

10/04/28 16:42:49 INFO mapred.JobClient:     ROWS=166580
10/04/28 16:42:49 INFO mapred.JobClient:     TOMBSTONES=1059387

On Wed, Apr 28, 2010 at 10:43 AM, Jonathan Ellis <jbellis@gmail.com> wrote:
> It sounds like either there is a fairly obvious bug, or you're doing
> something wrong. :)
>
> Can you reproduce against a single node?
>
> On Tue, Apr 27, 2010 at 5:14 PM, Joost Ouwerkerk <joost@openplaces.org> wrote:
>> Update: I ran a test whereby I deleted ALL the rows in a column
>> family, using a consistency level of ALL.  To do this, I mapped the
>> ColumnFamily and called remove on each row id.  There were 1.5 million
>> rows, so 1.5 million rows were deleted.
>>
>> I ran a counter job immediately after.  This job maps the same column
>> family and tests if any data is returned.  If not, it considers the
>> row a "tombstone".  If yes, it considers the row not deleted.  Below
>> are the hadoop counters for those jobs.  Note the fluctuation in the
>> number of rows with data over time, and the increase in time to map
>> the column family after the destroy job.  No other clients were
>> accessing cassandra during this time.
>>
>> I'm thoroughly confused.
>>
>> Count: started 13:02:30 EDT, finished 13:11:33 EDT (9 minutes 2 seconds):
>>   ROWS:        1,542,479
>>   TOMBSTONES:  69
>>
>> Destroy: started 16:48:45 EDT, finished 17:07:36 EDT (18 minutes 50 seconds)
>>   DESTROYED:  1,542,548
>>
>> Count: started 17:15:42 EDT, finished 17:31:03 EDT (15 minutes 21 seconds)
>>   ROWS 876,464
>>   TOMBSTONES   666,084
>>
>> Count: started 17:31:32, finished 17:47:16 (15mins, 44 seconds)
>>   ROWS 1,451,665
>>   TOMBSTONES   90,883
>>
>> Count: started 17:52:34, finished 18:10:28 (17mins, 53 seconds)
>>   ROWS 1,425,644
>>   TOMBSTONES   116,904
>>
>> On Tue, Apr 27, 2010 at 5:37 PM, Joost Ouwerkerk <joost@openplaces.org> wrote:
>>> Clocks are in sync:
>>>
>>> cluster04:~/cassandra$ dsh -g development "date"
>>> Tue Apr 27 17:36:33 EDT 2010
>>> Tue Apr 27 17:36:33 EDT 2010
>>> Tue Apr 27 17:36:33 EDT 2010
>>> Tue Apr 27 17:36:33 EDT 2010
>>> Tue Apr 27 17:36:34 EDT 2010
>>> Tue Apr 27 17:36:34 EDT 2010
>>> Tue Apr 27 17:36:34 EDT 2010
>>> Tue Apr 27 17:36:34 EDT 2010
>>> Tue Apr 27 17:36:34 EDT 2010
>>> Tue Apr 27 17:36:35 EDT 2010
>>> Tue Apr 27 17:36:35 EDT 2010
>>> Tue Apr 27 17:36:35 EDT 2010
>>>
>>> On Tue, Apr 27, 2010 at 5:35 PM, Nathan McCall <nate@vervewireless.com>
wrote:
>>>> Have you confirmed that your clocks are all synced in the cluster?
>>>> This may be the result of an unintentional read-repair occurring if
>>>> that were the case.
>>>>
>>>> -Nate
>>>>
>>>> On Tue, Apr 27, 2010 at 2:20 PM, Joost Ouwerkerk <joost@openplaces.org>
wrote:
>>>>> Hmm... Even after deleting with cl.ALL, I'm getting data back for some
>>>>> rows after having deleted them.  Which rows return data is
>>>>> inconsistent from one run of the job to the next.
>>>>>
>>>>> On Tue, Apr 27, 2010 at 1:44 PM, Joost Ouwerkerk <joost@openplaces.org>
wrote:
>>>>>> To check that rows are gone, I check that KeySlice.columns is empty.
 And as
>>>>>> I mentioned, immediately after the delete job, this returns the expected
>>>>>> number.
>>>>>> Unfortunately I reproduced with QUORUM this morning.  No node outages.
 I am
>>>>>> going to try ALL to see if that changes anything, but I am starting
to
>>>>>> wonder if I'm doing something else wrong.
>>>>>> On Mon, Apr 26, 2010 at 9:45 PM, Jonathan Ellis <jbellis@gmail.com>
wrote:
>>>>>>>
>>>>>>> How are you checking that the rows are gone?
>>>>>>>
>>>>>>> Are you experiencing node outages during this?
>>>>>>>
>>>>>>> DC_QUORUM is unfinished code right now, you should avoid using
it.
>>>>>>> Can you reproduce with normal QUORUM?
>>>>>>>
>>>>>>> On Sat, Apr 24, 2010 at 12:23 PM, Joost Ouwerkerk <joost@openplaces.org>
>>>>>>> wrote:
>>>>>>> > I'm having trouble deleting rows in Cassandra.  After running
a job that
>>>>>>> > deletes hundreds of rows, I run another job that verifies
that the rows
>>>>>>> > are
>>>>>>> > gone.  Both jobs run correctly.  However, when I run the
verification
>>>>>>> > job an
>>>>>>> > hour later, the rows have re-appeared.  This is not a case
of "ghosting"
>>>>>>> > because the verification job actually checks that there
is data in the
>>>>>>> > columns.
>>>>>>> >
>>>>>>> > I am running a cluster with 12 nodes and a replication factor
of 3.  I
>>>>>>> > am
>>>>>>> > using DC_QUORUM consistency when deleting.
>>>>>>> >
>>>>>>> > Any ideas?
>>>>>>> > Joost.
>>>>>>> >
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Jonathan Ellis
>>>>>>> Project Chair, Apache Cassandra
>>>>>>> co-founder of Riptano, the source for professional Cassandra
support
>>>>>>> http://riptano.com
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
>
>
> --
> Jonathan Ellis
> Project Chair, Apache Cassandra
> co-founder of Riptano, the source for professional Cassandra support
> http://riptano.com
>

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