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From Doug Meil <doug.m...@explorysmedical.com>
Subject Re: how get() works
Date Mon, 13 Feb 2012 14:05:57 GMT

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?"



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..
>Vamshi Krishna

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