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From Kais Ahmed <k...@neteck-fr.com>
Subject Re: Cassandra read reapair
Date Mon, 27 May 2013 10:01:27 GMT
Hi aaron,

I was sure that  phpcassa use QUORUM for W and R by default, but you're
right, the default CL for R AND W is ONE.

We are in this configuration W + R < N, how can i do to repair some keys
that always return inconsistent data.

Thanks,









2013/5/24 Kais Ahmed <kais@neteck-fr.com>

> Hi aaron an thanks,
>
>
> > If you are reading and writing at CL QUOURM and getting inconsistent
> results that sounds like a bug. If you are mixing the CL levels such that R
> + W <= N then it's expected behaviour.
> I think it's a bug, it concern only some keys (~200 over 120 000 keys) on
> one column family,
>
> As I understand it, if  R+W <= N it's expected behaviour at a moment, but
> read repair will correct the inconsistent data (related to
> read_repair_chance value)
> and the next query will return a consistent data , right ?
>
> Here is an exemple of a result that i have on a key (keyspace RF 3), 3
> differents replicas :
>
> [default@prod] ASSUME contacts_timeordered KEYS AS ascii;
>
> [default@prod] get contacts_timeordered['1425185-IGNORED'];
> => (column=1a927740-97ec-11e2-ab16-a1afd66a735e, value=363838353936,
> timestamp=1364505108842098)
> => (column=1a93d5b0-97ec-11e2-888c-2bf068e0f754, value=31373930303330,
> timestamp=1364505108851088)
> => (column=b5c559c0-9d0f-11e2-8682-f7ecd4112689, value=32343130303930,
> timestamp=1365070157421869)
> => (column=7ba22b90-b48b-11e2-a2c2-914573921d9f, value=32353031353039,
> timestamp=1367652194221857)
> => (column=63ef5d80-b7e8-11e2-abf8-593c289227cd, value=32383435323830,
> timestamp=1368021951146575)
> => (column=d6383fc0-b810-11e2-a880-bd2ecacbaee3, value=31363334363737,
> timestamp=1368039322753824)
> => (column=f47d8e60-bd3f-11e2-88f4-533a93fe9432, value=32373938313038,
> timestamp=1368609315699785)
> => (column=c5bfe060-bf8e-11e2-ab1f-07be407aff58, value=32333634353034,
> timestamp=1368863069848610)
> => (column=f07ae4b0-c42f-11e2-8064-9794e872eb2b, value=363838353936,
> timestamp=1369372095163129)
> Returned 9 results.
> Elapsed time: 10 msec(s).
>
> [default@prod] get contacts_timeordered['1425185-IGNORED'];
> => (column=b5c559c0-9d0f-11e2-8682-f7ecd4112689, value=32343130303930,
> timestamp=1365070157421869)
> => (column=7ba22b90-b48b-11e2-a2c2-914573921d9f, value=32353031353039,
> timestamp=1367652194221857)
> => (column=63ef5d80-b7e8-11e2-abf8-593c289227cd, value=32383435323830,
> timestamp=1368021951146575)
> => (column=d6383fc0-b810-11e2-a880-bd2ecacbaee3, value=31363334363737,
> timestamp=1368039322753824)
> => (column=f47d8e60-bd3f-11e2-88f4-533a93fe9432, value=32373938313038,
> timestamp=1368609315699785)
> => (column=c5bfe060-bf8e-11e2-ab1f-07be407aff58, value=32333634353034,
> timestamp=1368863069848610)
> => (column=f07ae4b0-c42f-11e2-8064-9794e872eb2b, value=363838353936,
> timestamp=1369372095163129)
> Returned 7 results.
> Elapsed time: 7.49 msec(s).
>
> [default@prod] get contacts_timeordered['1425185-IGNORED'];
> => (column=1a93d5b0-97ec-11e2-888c-2bf068e0f754, value=31373930303330,
> timestamp=1364505108851088)
> => (column=b5c559c0-9d0f-11e2-8682-f7ecd4112689, value=32343130303930,
> timestamp=1365070157421869)
> => (column=7ba22b90-b48b-11e2-a2c2-914573921d9f, value=32353031353039,
> timestamp=1367652194221857)
> => (column=63ef5d80-b7e8-11e2-abf8-593c289227cd, value=32383435323830,
> timestamp=1368021951146575)
> => (column=d6383fc0-b810-11e2-a880-bd2ecacbaee3, value=31363334363737,
> timestamp=1368039322753824)
> => (column=f47d8e60-bd3f-11e2-88f4-533a93fe9432, value=32373938313038,
> timestamp=1368609315699785)
> => (column=c5bfe060-bf8e-11e2-ab1f-07be407aff58, value=32333634353034,
> timestamp=1368863069848610)
> => (column=f07ae4b0-c42f-11e2-8064-9794e872eb2b, value=363838353936,
> timestamp=1369372095163129)
> Returned 8 results.
> Elapsed time: 9.37 msec(s).
>
> Do I have to change read_repair_chance to 1 to correct the inconsistency,
> nodetool repair don't solve it.
>
> Thanks a lot,
>
>
>
>
>
> 2013/5/23 aaron morton <aaron@thelastpickle.com>
>
>> If you are reading and writing at CL QUOURM and getting inconsistent
>> results that sounds like a bug. If you are mixing the CL levels such that R
>> + W <= N then it's expected behaviour.
>>
>>
>> Can you reproduce the issue outside of your app ?
>>
>> Cheers
>>
>>    -----------------
>> Aaron Morton
>> Freelance Cassandra Consultant
>> New Zealand
>>
>> @aaronmorton
>> http://www.thelastpickle.com
>>
>> On 21/05/2013, at 8:55 PM, Kais Ahmed <kais@neteck-fr.com> wrote:
>>
>> > Checking you do not mean the row key is corrupt and cannot be read.
>> Yes, i can read it but all read don't return the same result except for
>> CL ALL
>>
>> > By default in 1.X and beyond the default read repair chance is 0.1, so
>> it's only enabled on 10% of requests.
>> You are right read repair chance is set to 0.1, but i launched a read
>> repair which did not solved the problem. Any idea?
>>
>> >What CL are you writing at ?
>> All write are in CL QUORUM
>>
>> thank you aaron for your answer.
>>
>>
>> 2013/5/21 aaron morton <aaron@thelastpickle.com>
>>
>>> Only some keys of one CF are corrupt.
>>>
>>> Checking you do not mean the row key is corrupt and cannot be read.
>>>
>>> I thought using CF ALL, would correct the problem with READ REPAIR, but by
>>> returning to CL QUORUM, the problem persists.
>>>
>>> By default in 1.X and beyond the default read repair chance is 0.1, so
>>> it's only enabled on 10% of requests.
>>>
>>> In the absence of further writes all reads (at any CL) should return the
>>> same value.
>>>
>>> What CL are you writing at ?
>>>
>>> Cheers
>>>
>>>    -----------------
>>> Aaron Morton
>>> Freelance Cassandra Consultant
>>> New Zealand
>>>
>>> @aaronmorton
>>> http://www.thelastpickle.com
>>>
>>> On 19/05/2013, at 1:28 AM, Kais Ahmed <kais@neteck-fr.com> wrote:
>>>
>>> Hi all,
>>>
>>> I encountered a consistency problem one some keys using phpcassa and
>>> Cassandra 1.2.3 since a server crash
>>>
>>> Only some keys of one CF are corrupt.
>>>
>>> I lauched a nodetool repair that successfully completed but don't
>>> correct the issue.
>>>
>>>
>>>
>>> When i try to get a corrupt Key with :
>>>
>>> CL ONE, the result contains 7 or 8 or 9 columns
>>>
>>> CL QUORUM, result contains 8 or 9 columns
>>>
>>> CL ALL, the data is consistent and returns always 9 columns
>>>
>>>
>>> I thought using CF ALL, would correct the problem with READ REPAIR, but by
>>> returning to CL QUORUM, the problem persists.
>>>
>>>
>>> Thank you for your help
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>

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