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From kranthi reddy <kranthili2...@gmail.com>
Subject Re: Porting SQL DB into HBASE
Date Mon, 12 Apr 2010 08:55:48 GMT
HI jonathan,

Sorry for the late response. Missed your reply.

The problem is, around 80% (400) of the tables are static tables and the
remaining 20% (100) are dynamic tables that are updated on a daily basis.
The problem is denormalising these 20% tables is also extremely difficult
and we are planning to port them directly into hbase. And also denormalising
these tables would lead to a lot of redundant data.

Static tables have number of entries varying in hundreds and mostly less
than 1000 entries (rows). Where as the dynamic tables have more than 20,000
entries and each entry might be updated/modified at least once in a week.

Regards,
kranthi


On Wed, Mar 31, 2010 at 10:23 PM, Jonathan Gray <jgray@facebook.com> wrote:

> Kranthi,
>
> HBase can handle a good number of tables, but tens or maybe a hundred.  If
> you have 500 tables you should definitely be rethinking your schema design.
>  The issue is less about HBase being able to handle lots of tables, and much
> more about whether scattering your data across lots of tables will be
> performant at read time.
>
>
> 1)  Impossible to answer that question without knowing the schemas of the
> existing tables.
>
> 2)  Not really any relation between fault tolerance and the number of
> tables except potentially for recovery time but this would be the same with
> few, very large tables.
>
> 3)  No difference in write performance.  Read performance if doing simple
> key lookups would not be impacted, but most like having data spread out like
> this will mean you'll need joins of some sort.
>
> Can you tell more about your data and queries?
>
> JG
>
> > -----Original Message-----
> > From: kranthi reddy [mailto:kranthili2020@gmail.com]
> > Sent: Wednesday, March 31, 2010 3:05 AM
> > To: hbase-user@hadoop.apache.org
> > Subject: Porting SQL DB into HBASE
> >
> > Hi all,
> >
> >         I have run into some trouble while trying to port SQL DB to
> > Hbase.
> > The problem is my SQL DB has around 500 tables (approx) and it is very
> > badly
> > designed. Around 45-50 tables could be denormalised into a single table
> > and
> > the remaining tables are static tables. My doubts are
> >
> > 1) Is it possible to port this DB (Tables) to Hbase? If possible how?
> > 2) How many tables can Hbase support with tolerance towards failure?
> > 3) When so many tables are inserted, how is the performance going to be
> > effected? Will it remain same or degrade?
> >
> > One possible solution I think is using column family for each table.
> > But as
> > per my knowledge and previous experiments, I found Hbase isn't stable
> > when
> > column families are more than 5.
> >
> > Since every day large quantities of data is ported into the DataBase,
> > stability and fail proof system is highest priority.
> >
> > Hoping for a positive response.
> >
> > Thank you,
> > kranthi
>



-- 
Kranthi Reddy. B
Room No : 98
Old Boys Hostel
IIIT-HYD

-----------

I don't know the key to success, but the key to failure is trying to impress
others.

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