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Accumulo, mail # user - Table splitting


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Re: Table splitting
Eric Newton 2012-12-12, 18:29
Well, you have to assume the tablet does not get moved for balancing or
recovery.

-Eric
On Wed, Dec 12, 2012 at 1:27 PM, ameet kini <[EMAIL PROTECTED]> wrote:

>
> Ok, so in short, assuming that there's sufficient local disk space, a
> given tablet having all its blocks local relies on HDFS's guarantee that
> the first replica of a block will be local as long as the tablet server is
> also a data node. Yes?
>
>
>
> On Wed, Dec 12, 2012 at 1:18 PM, Eric Newton <[EMAIL PROTECTED]>wrote:
>
>> Check out o.a.a.server.util.LocalityCheck
>>
>> -Eric
>>
>>
>> On Wed, Dec 12, 2012 at 1:17 PM, John Vines <[EMAIL PROTECTED]> wrote:
>>
>>> When a file gets written to hdfs, there is a guarantee the file is local
>>> as long as that systems disks are not full. Accumulo does not have a
>>> locality guarantee as tablets will migrate on occasion. However, as data is
>>> added, major compactions will occur which will restore locality.
>>>  On Dec 12, 2012 1:09 PM, "ameet kini" <[EMAIL PROTECTED]> wrote:
>>>
>>>>
>>>> Along these lines....
>>>>
>>>> Can someone help me understand how tablets map to files on disk in
>>>> HDFS? From what I understand, after a compaction, there may be one (or
>>>> more?) files on HDFS for a given tablet. Each file can consist of multiple
>>>> HDFS blocks. Does Accumulo guarantee that the tablet serving a given data
>>>> range finds all its blocks locally? If so, how does it keep this guarantee?
>>>> Wouldn't HDFS distribute these blocks around based on HDFS balancing
>>>> strategy?
>>>>
>>>> Thanks,
>>>> Ameet
>>>>
>>>> On Tue, Dec 11, 2012 at 9:37 AM, William Slacum <
>>>> [EMAIL PROTECTED]> wrote:
>>>>
>>>>> Tablets will split automatically, down to the granularity of a row.
>>>>>
>>>>>
>>>>> On Tue, Dec 11, 2012 at 9:32 AM, Mathias Herberts <
>>>>> [EMAIL PROTECTED]> wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> I've read the user manual for v1.4.2 and I have not seen any mention
>>>>>> of automatic tablet splitting. Is there such a thing in Accumulo or is
>>>>>> pre-splitting the only way to split a table?
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> Mathias.
>>>>>>
>>>>>
>>>>>
>>>>
>>
>