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HBase, mail # user - Region hot spotting


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RE: Region hot spotting
Ajay Bhosle 2012-11-22, 13:28
We are not fetching single row back. Hashing really helped, the data is now
almost equally split between the servers. Thanks a lot.

-Ajay

-----Original Message-----
From: Michael Segel [mailto:[EMAIL PROTECTED]]
Sent: Thursday, November 22, 2012 2:52 AM
To: [EMAIL PROTECTED]
Subject: Re: Region hot spotting

Salting is not a good idea and I don't know why people suggest it.

Case in point.... you want to fetch a single row/record back. Because the
salt is arbitrary, you will need to send N number of get()s one for each
salt value.
Doing a simple one way hash of the data, even appending the data, would be a
better idea. Note that if you are worried about key length, you can do the
hash and take the first N bytes and then append the row to it. It should
give you enough of a spread of hash values that you don't have to worry
about hotspots.

HTH

-Mike

On Nov 21, 2012, at 2:44 AM, ramkrishna vasudevan
<[EMAIL PROTECTED]> wrote:

> Hi
> This link is pretty much useful.  But still there too it says if you dont
> pre split you need to wait for the salting to help you from hotspotting
> till the region gets splitted.
>
> Mohammad just pointing this to say the usefulness of presplitting
> definitely your's is a good pointer to Ajay. :)
>
> Regards
> Ram
>
> On Wed, Nov 21, 2012 at 1:59 PM, Mohammad Tariq <[EMAIL PROTECTED]>
wrote:
>
>> Hello Ajay,
>>
>> You can use 'salting' if you don't want to presplit your table. You might
>> this link useful :
>>
>>
http://blog.sematext.com/2012/04/09/hbasewd-avoid-regionserver-hotspotting-d
espite-writing-records-with-sequential-keys/
>>
>> HTH
>>
>> Regards,
>>    Mohammad Tariq
>>
>>
>>
>> On Wed, Nov 21, 2012 at 1:49 PM, ramkrishna vasudevan <
>> [EMAIL PROTECTED]> wrote:
>>
>>> Hotspotting is bound to happen until the region starts splitting and
gets
>>> assigned to diff region servers.
>>>
>>> Regards
>>> Ram
>>>
>>> On Wed, Nov 21, 2012 at 12:49 PM, Ajay Bhosle
>>> <[EMAIL PROTECTED]>wrote:
>>>
>>>> Hi,
>>>>
>>>>
>>>>
>>>> I am inserting some data in hbase which is getting hot spotted in a
>>>> particular server. The format of the row key is (0 or
>>>> 1)|[timestamp]_[sequence].  Basically I want to add log information to
>>>> hbase
>>>> and search the records based on range of dates.
>>>>
>>>>
>>>>
>>>> Can someone suggest any configuration changes or any ideas on how the
>> row
>>>> key should be design. I do not want to specify the splits while
>> creating
>>>> table.
>>>>
>>>>
>>>>
>>>> Thanks
>>>>
>>>> Ajay
>>>>
>>>>
>>>>
>>>>
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