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From Bradford Stephens <bradfordsteph...@gmail.com>
Subject Re: Hi, i am still puzzeld to find a row key by a cell.
Date Mon, 17 Aug 2009 19:24:14 GMT
Just reiterating with JGray says -- usually, when you need a secondary
index, you can get away with denormalizing and duplicating your data.

On Mon, Aug 17, 2009 at 9:30 AM, Jonathan Gray<jlist@streamy.com> wrote:
> This is possible by checking the values in your client, through server-side
> filters (see org.apache.hadoop.hbase.filter), or with secondary indexing (as
> described in my previous e-mail).
>
> In the first two cases, you are doing a full table scan so it is very
> inefficient.  That's the same as it would be in an RDBMS if you were not
> using secondary indexes, however.
>
> HBase has limited secondary indexing support, but do not expect the
> flexibility and performance you get from an RDBMS secondary index.
>
> If this is central to your usage of HBase, make sure that HBase is what you
> want and take another look at your schema to see if there might be a better
> design to prevent needing heavy indexing or table scanning.
>
> JG
>
> Rocks wrote:
>>
>> Thanks for you answer.
>> however, what i want to do just likes "where" keyword of SQL in RDBMS. Is
>> it impossible in hbase ?
>>
>> On Mon, Aug 17, 2009 at 2:58 PM, Ryan Rawson <ryanobjc@gmail.com> wrote:
>>
>>> hey,
>>>
>>> That isn't how hbase (or even rdbms) work.  Instead you can retrieve
>>> rows based on their row key. Otherwise you will have to read the
>>> entire table to find just that 1 row. Yes this is as inefficient as it
>>> sounds.
>>>
>>> If you frequently have this issue, you may need to build and maintain
>>> secondary indexes. Unlike relational dbs, there is no built in support
>>> for this, you have to write your app to handle this.
>>>
>>> -yran
>>>
>>>
>>>
>>> On Sun, Aug 16, 2009 at 11:51 PM, lei wang<hbasemaillist@gmail.com>
>>> wrote:
>>>>
>>>> Hi, if a know a cell in a hbase for its column:<qualifer>:value,  i
need
>>>
>>> to
>>>>
>>>> know which row key it belongs to. I searched the HBase api several
>>>> times,
>>>> but i can not find the right method to solve my problem. Thanks for
>>>> one's
>>>> suggestion to me.
>>>>
>>
>



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http://www.roadtofailure.com -- The Fringes of Scalability, Social
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