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From: Cosmin Lehene <clehene@adobe.com>
To: "user@hbase.apache.org" <user@hbase.apache.org>
CC: "hbase-user@hadoop.apache.org" <hbase-user@hadoop.apache.org>
Date: Fri, 16 Jul 2010 10:24:37 +0100
Subject: Re: transactional hbase
Thread-Topic: transactional hbase
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Hi,=20

HBase supports row-level atomic operations. If you need to update more than=
 a row in a single transaction you'll have to use a coordination mechanism.=
 You can use Zookeeper for that.=20

However you can also evaluate whether you can't use a single table for your=
 operation by taking advantage of the columnar model. Basically you can enc=
ode an entire star schema in a single table in HBase. Each family can act a=
s a table. So when you have  1-M relations you can just write all the value=
s (M) in a single row (1). This way you could use a single put operation to=
 update your "child" entities.

Cosmin=20

On Jul 16, 2010, at 12:57 AM, N Kapshoo wrote:

> Can someone please point me to some more info? I am concerned about
> inconsistent data and am evaluating risk...
> Thanks.
>=20
> On Thu, Jul 15, 2010 at 3:11 PM, N Kapshoo <nkapshoo@gmail.com> wrote:
>> Hi,
>>=20
>> I have a write API call that does 3 puts (2 puts  to one table and a
>> 3rd put to a second table). How do I go about making sure that these
>> all happen or none happen at all?  In short, an atomic transaction.
>>=20
>> I read up a little bit about the TransactionManager and that I need to
>> modify hbase-site.xml to make these TransactionalRegion Servers. Can
>> someone point me to some more info about the same? What versions, what
>> performance impacts etc? Are there some good urls that anyone can
>> share?
>>=20
>> I am using HBase 0.20.3 at this time. I dont believe transactions are
>> supported in this version. If I were to go live and then decide to use
>> transactions later, how should I plan on an upgrade?
>>=20
>> Thanks.
>>=20