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Posted to user@hbase.apache.org by Jan Lukavský <ja...@firma.seznam.cz> on 2013/05/17 15:40:08 UTC

Scanner returning keys out of order

Hi all,

we are seeing very strange behavior of HBase (version 0.90.6-cdh3u5) in 
the following scenario:

  1) Open scanner and start scanning.
  2) Check order of returned keys (simple test if next key is 
lexigraphically greater than the previous one).
  3) The check may occasionally fail.

When we investigated this a bit, we saw major compaction occurring on 
the scanned region precisely in the time of the check failure. 
Interesting is that the compaction occurred on a column family that was 
not actually involved in the scanning. Has anyone else seen this? Is it 
possible that this is fixed in any higher version of HBase?

Thanks,
  Jan

Re: Scanner returning keys out of order

Posted by Jan Lukavský <ja...@firma.seznam.cz>.

Hi JM,

thanks for reply, we will upgrade and check if the problem goes away.

Cheers,
  Jan

On 17.5.2013 15:44, Jean-Marc Spaggiari wrote:
> Hi Jan,
>
> 0.90.6 is a very old version of HBase... Will you have a chance to migrate
> to a more recent one? Most of your issues might probably be already fixed.
>
> JM
>
> 2013/5/17 Jan Lukavský <ja...@firma.seznam.cz>
>
>> Hi all,
>>
>> we are seeing very strange behavior of HBase (version 0.90.6-cdh3u5) in
>> the following scenario:
>>
>>   1) Open scanner and start scanning.
>>   2) Check order of returned keys (simple test if next key is
>> lexigraphically greater than the previous one).
>>   3) The check may occasionally fail.
>>
>> When we investigated this a bit, we saw major compaction occurring on the
>> scanned region precisely in the time of the check failure. Interesting is
>> that the compaction occurred on a column family that was not actually
>> involved in the scanning. Has anyone else seen this? Is it possible that
>> this is fixed in any higher version of HBase?
>>
>> Thanks,
>>   Jan
>>
>>
>>

Re: Scanner returning keys out of order

Posted by Jean-Marc Spaggiari <je...@spaggiari.org>.

Hi Jan,

0.90.6 is a very old version of HBase... Will you have a chance to migrate
to a more recent one? Most of your issues might probably be already fixed.

JM

2013/5/17 Jan Lukavský <ja...@firma.seznam.cz>

> Hi all,
>
> we are seeing very strange behavior of HBase (version 0.90.6-cdh3u5) in
> the following scenario:
>
>  1) Open scanner and start scanning.
>  2) Check order of returned keys (simple test if next key is
> lexigraphically greater than the previous one).
>  3) The check may occasionally fail.
>
> When we investigated this a bit, we saw major compaction occurring on the
> scanned region precisely in the time of the check failure. Interesting is
> that the compaction occurred on a column family that was not actually
> involved in the scanning. Has anyone else seen this? Is it possible that
> this is fixed in any higher version of HBase?
>
> Thanks,
>  Jan
>
>
>