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From Edward Capriolo <edlinuxg...@gmail.com>
Subject Re: web applications and multiple db calls per page view
Date Wed, 14 Jul 2010 16:22:44 GMT
On Wed, Jul 14, 2010 at 11:30 AM, S Ahmed <sahmed1020@gmail.com> wrote:
> I haven't built it yet, I am in the planning stages as I don't have a solid
> grasp of distributing databases just yet.
>
> I was just going through an average page lifecycyle, and was just concerned
> at a high level on what I should be looking out for and what expectations I
> should have.
>
>>> Or are you
>>>just asking if you saw that theoretical latency what would you do
>>>next? Future troubleshooting ?
> Well I have been reading some benchmarks, and if say the average query takes
> 30ms and I am making 10 calls, things can start adding up so I was concerned
> yes.
>
>
> On Wed, Jul 14, 2010 at 11:24 AM, Edward Capriolo <edlinuxguru@gmail.com>wrote:
>
>> On Wed, Jul 14, 2010 at 11:12 AM, S Ahmed <sahmed1020@gmail.com> wrote:
>> > If I build a forum application like vbulletin on top on hbase, I can
>> forsee
>> > that each page view will have multiple calls to hbase.
>> >
>> > Let's picture someone viewing a particular thread (question) on the
>> website:
>> >
>> > 0. load the current website object (remember this is a multi-tenancy
>> > application, Saas forum application).
>> > 1. verify user is logged in.
>> > 2. get user profile / permissions if logged in
>> > 3. get current forum object
>> > 4. get current thread object
>> > 5. get all replies to thread
>> >
>> > And probably 2-3 calls will come into the picture as i progress.
>> >
>> > If each call takes 100ms, this isn't going to be a 'snappy' response now
>> is
>> > it?
>> >
>> > Or is there a way to batch calls to minimize the chattyness?
>> >
>>
>> If you are pooling/reusing hbase objects intelligently have a good
>> schema design, good caching, and enough hardware you should not be
>> seeing requests take that long. I do not want to promise 1ms
>> performance on every request but that is pretty common.
>>
>> You started your message with  'If I build a forum application'. Have
>> you done this? If so are you actually seeing 100ms latency? Or are you
>> just asking if you saw that theoretical latency what would you do
>> next? Future troubleshooting ?
>>
>

If you want to discuss performance please reference what benchmark you
are talking about. A popular benchmark is:
http://www.brianfrankcooper.net/pubs/ycsb.pdf

As the amount of data per node grows, and the requests per node grow,
performance will degrade. However Hbase is a scale out architecture,
so you combat data per node and requests per node by adding more
nodes. See the attached PDF for Elastic speedup, scale-out.

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