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From Ryan Rawson <ryano...@gmail.com>
Subject Re: Questions about HBase
Date Tue, 02 Mar 2010 06:57:23 GMT
The ROOT/META are hosted on a regionserver so the system is
self-referential and self-hosting, furthermore it reduces the
dependency on the master to just a single duty of reassigning regions
as necessary.

-ryan

On Mon, Mar 1, 2010 at 7:36 PM, William Kang <weliam.cloud@gmail.com> wrote:
> And another question, why the ROOT table and META tables are not in the
> HBaseMaster's memory? Would this greatly degrade the performance?
> Thanks.
>
>
> William
>
>
> On Mon, Mar 1, 2010 at 5:33 PM, Erik Holstad <erikholstad@gmail.com> wrote:
>
>> On Mon, Mar 1, 2010 at 2:16 PM, Ryan Rawson <ryanobjc@gmail.com> wrote:
>>
>> > Hi,
>> >
>> > 1.  We use in-memory indexes to get fast random reads.  Our index
>> > tells us to read block X of a file only retrieving a small amount of
>> > the file to satisfy the user's read.
>> >
>> > 2.  The row locking is not global - for each row there can only be 1
>> > thread doing a put at a time.  This serializes all puts to a single
>> > row. It is NOT global.
>> >
>>
>> So, this is me not understanding the difference between global locking and
>> waiting in a line until the tasks ahead of you are done :)
>>
>> >
>> > On Mon, Mar 1, 2010 at 12:36 PM, William Kang <weliam.cloud@gmail.com>
>> > wrote:
>> > > Hi guys,
>> > > I am new to HBase and have several questions. Would anybody kindly
>> answer
>> > > some of them?
>> > >
>> > > 1. Why HBase could provide a low-latency random access to files
>> compared
>> > to
>> > > HDFS?
>> > >
>> > > 2. By default, Only a single row at a time may be locked. Is it a
>> single
>> > > client who can only lock one or is it globally can only lock one?  If
>> > this
>> > > is the case, by default, will the performance be really bad?
>> > >
>> > > Many thanks!
>> > >
>> > >
>> > > William
>> > >
>> >
>>
>>
>>
>> --
>> Regards Erik
>>
>

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