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From Amandeep Khurana <ama...@gmail.com>
Subject Re: HBase -- unique constraints
Date Fri, 30 Oct 2009 00:49:56 GMT
anwers inline

On Thu, Oct 29, 2009 at 5:24 PM, learningtapestry <satishb10@yahoo.com>wrote:

>
> I am evaluating if HBase is right for a small prototype I am developing.
>
> Please help me understand a few things:
>
> 1. Can I do something like this in RDBMS -- "select * from table WHERE
> column LIKE '%xyz%'"
>

You can create ValueFilters and scan through a table. But there is no query
language as such.


> 2. How should we place constraints? For example, if I have a Users table,
> and one column is "login_name". How can I ensure that no two people create
> the same login name? Is there a constraint I can place or something
> similar?
>

It has to be in your application. Nothing in hbase gives this feature afaik


>
> 3. Is there something with HBase tables that I CANNOT do? If there is, what
> is the strategy I have to use?
>

There is no concept of relational data. Its a different way of thinking
about data. Everything is denormalized. For details, read the BigTable
paper.


>
> 4. For something not possible with HBase today, can I simply use the
> MapReduce framework that comes with Hadoop over the HBase tables?
>

What do you mean? You can surely write MR jobs that talk to HBase but thats
not a workaround to RDBMS kind of stuff. If you need RDBMS kind of
functionality, maybe HBase is not for you.


>
> Thanks in advance
> --
> View this message in context:
> http://www.nabble.com/HBase----unique-constraints-tp26123147p26123147.html
> Sent from the HBase User mailing list archive at Nabble.com.
>
>

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