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From Ryan Rawson <ryano...@gmail.com>
Subject Re: Questions about HBase
Date Tue, 02 Mar 2010 06:58:53 GMT
I guess I interpret 'global locking' as in "affects all threads
regardless of if they are interested in a particular row or not".  Row
locks only affect threads that are interested in said row.  Unrelated
threads are unaffected.  Sorry if there is a little duplication of
words here, it's a fairly subtle yet important issue.



On Mon, Mar 1, 2010 at 2:33 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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