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HBase >> mail # user >> Parallel scan in HBase


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Farrokh Shahriari 2013-02-01, 13:52
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lars hofhansl 2013-02-01, 15:46
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Mohammad Tariq 2013-02-01, 16:40
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Re: Parallel scan in HBase
If you run a SQL query that does aggregation (i.e. uses a built-in
aggregation function like COUNT or does a GROUP BY), Phoenix will
orchestrate the running of a set of queries in parallel, segmented along
your row key (driven by the start/stop key plus region boundaries). We
take advantage of a nifty feature that Lars added where you can pass in
your own ExecutorService to an HTable, so you could do something similar.

Regards,

     James

On 02/01/2013 08:40 AM, Mohammad Tariq wrote:
> Do you need to scan each n every row within that range?Or you need specific
> rows based on some filter?
>
> Warm Regards,
> Tariq
> https://mtariq.jux.com/
> cloudfront.blogspot.com
>
>
> On Fri, Feb 1, 2013 at 9:16 PM, lars hofhansl <[EMAIL PROTECTED]> wrote:
>
>> The scan contract in HBase is that all rows are returned in order, so all
>> regions have to be traversed in order as well.
>> It would be nice to add some facility to HBase to performs the scanning in
>> parallel.
>>
>>
>>
>> ________________________________
>>   From: Farrokh Shahriari <[EMAIL PROTECTED]>
>> To: [EMAIL PROTECTED]
>> Sent: Friday, February 1, 2013 5:52 AM
>> Subject: Parallel scan in HBase
>>
>> Hi there
>> I have two question about scan in Hbase :
>> 1) Does scan operation with specific filter run in parallel on different
>> regionservers ?
>> 2) I wanna know whether this code runs at client side for searching the
>> retrieved results or not ?
>>
>>           for (Result result : scanner1) {
>>                           for (KeyValue kv : result.raw()) {
>>                           //
>>                           // some coeds
>>                           //
>>                       }
>>                 }
>>
>>
>> Farrokh Shahriari
>>
>
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Farrokh Shahriari 2013-02-02, 04:54
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Mohammad Tariq 2013-02-01, 14:02
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Farrokh Shahriari 2013-02-01, 14:57
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Alexander Ignatov 2013-02-01, 15:07
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Jean-Marc Spaggiari 2013-02-01, 15:29