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From Doug Meil <doug.m...@explorysmedical.com>
Subject Re: how get() works
Date Tue, 14 Feb 2012 16:09:49 GMT

I say "basically" because inside a Region there are Stores, and for each
Store there are StoreFiles.  For more info see:

http://hbase.apache.org/book.html#regions.arch





On 2/14/12 11:06 AM, "Doug Meil" <doug.meil@explorysmedical.com> wrote:

>
>Keys are stored in sorted order, it's basically a binary search.
>
>
>
>
>On 2/14/12 9:31 AM, "Vamshi Krishna" <vamshi2105@gmail.com> wrote:
>
>>Thank you Doug..
>>
>>Onemore question is, If a particular region is found by looking at the
>>range handeled by it, How  is search performed within that region to find
>>requested rowKey? Is it by linear search or binary search or any other
>>algorithm? Or for every row in that region, is there any hash value
>>stored
>>and hash lookup takes place to get that rowKey's value?   what happens
>>really within that region?
>>
>>On Mon, Feb 13, 2012 at 7:35 PM, Doug Meil
>><doug.meil@explorysmedical.com>wrote:
>>
>>>
>>> re:  "Now if that RegionServer has multiple
>>> regions on it, how does the request get transfered to a correct region
>>> which has the requested rowKey?"
>>>
>>> See...
>>>
>>> 
>>>http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/client/HTable.ht
>>>m
>>>l#
>>> getRegionLocation%28byte[],%20boolean%29
>>>
>>> As described in Arch/Client in the book, the Hbase client knows all the
>>> regions and the the region boundaries from META.
>>>
>>>
>>>
>>>
>>> On 2/13/12 1:46 AM, "Vamshi Krishna" <vamshi2105@gmail.com> wrote:
>>>
>>> >Hi all, i have a small basic doubt regarding get() method which is
>>>used in
>>> >HTable. From the hbase book, under 8.3.Client section, i understood
>>>that,
>>> >when ever client sends a request like get(rowKey) on any htable
>>>instance,
>>> >from ROOT and META, it knows the regionserver where the regions
>>>holding
>>> >that requested rowKey is present. Now if that RegionServer has
>>>multiple
>>> >regions on it, how does the request get transfered to a correct region
>>> >which has the requested rowKey? (will there be again any lookups for
>>>it?)
>>> >
>>> >Is it like this:  The RegionServer holds the information about all the
>>> >regions it is hosting, so looking at the respective ranges of rows in
>>>each
>>> >region a region is selected, and passing that request to that
>>>appropriate
>>> >region.  Am i correct? if not, correct me.
>>> >
>>> >Onemore question is, If a particular region is found by looking at the
>>> >range handeled by it, How  is search performed within that region to
>>>find
>>> >requested rowKey? Is it by linear search or binary search or any other
>>> >algorithm? Or for every row in that region, is there any hash value
>>>stored
>>> >and hash lookup takes place to get that rowKey's value?   what happens
>>> >really within that region?
>>> >
>>> >
>>> >can anybody help, please..
>>> >--
>>> >*Regards*
>>> >*
>>> >Vamshi Krishna
>>> >*
>>>
>>>
>>>
>>
>>
>>-- 
>>*Regards*
>>*
>>Vamshi Krishna
>>*
>
>
>



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