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HBase, mail # user - Region Splits


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Re: Region Splits
Nicolas Spiegelberg 2011-11-22, 17:29
No.  The purpose of major compactions is to merge & dedupe within a region
boundary.  Compactions will not alter region boundaries, except in the
case of splits where a compaction is necessary to filter out any Rows from
the parent region that are no longer applicable to the daughter region.

On 11/22/11 9:04 AM, "Srikanth P. Shreenivas"
<[EMAIL PROTECTED]> wrote:

>Will major compactions take care of merging "older" regions or adding
>more key/values to them as number of regions grow?
>
>Regard,
>Srikanth
>
>-----Original Message-----
>From: Amandeep Khurana [mailto:[EMAIL PROTECTED]]
>Sent: Monday, November 21, 2011 7:25 AM
>To: [EMAIL PROTECTED]
>Subject: Re: Region Splits
>
>Mark,
>
>Yes, your understanding is correct. If your keys are sequential
>(timestamps
>etc), you will always be writing to the end of the table and "older"
>regions will not get any writes. This is one of the arguments against
>using
>sequential keys.
>
>-ak
>
>On Sun, Nov 20, 2011 at 11:33 AM, Mark <[EMAIL PROTECTED]> wrote:
>
>> Say we have a use case that has sequential row keys and we have rows
>> 0-100. Let's assume that 100 rows = the split size. Now when there is a
>> split it will split at the halfway mark so there will be two regions as
>> follows:
>>
>> Region1 [START-49]
>> Region2 [50-END]
>>
>> So now at this point all inserts will be writing to Region2 only
>>correct?
>> Now at some point Region2 will need to split and it will look like the
>> following before the split:
>>
>> Region1 [START-49]
>> Region2 [50-150]
>>
>> After the split it will look like:
>>
>> Region1 [START-49]
>> Region2 [50-100]
>> Region3 [150-END]
>>
>> And this pattern will continue correct? My question is when there is a
>>use
>> case that has sequential keys how would any of the older regions every
>> receive anymore writes? It seems like they would always be stuck at
>> MaxRegionSize/2. Can someone please confirm or clarify this issue?
>>
>> Thanks
>>
>>
>>
>>
>>
>
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