Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Threaded View
HBase >> mail # user >> Using doubles and longs as ordering row values


Copy link to this message
-
Re: Using doubles and longs as ordering row values

On 12/01/2012 10:01 AM, David Koch wrote:
> Hello Lars,
>
> Thank you. Where can I find the lily library? I can't find it on github or
> Google.
http://www.lilyproject.org/lily/index.html
>
> /David
>
>
> On Fri, Nov 30, 2012 at 3:54 AM, lars hofhansl <[EMAIL PROTECTED]> wrote:
>
>> As I said, look at the lily library they have solved exactly that problem,
>> I've used that before.
>>
>> It has encodings for Ints/Longs/Floats/Doubles/BigDecimals, to encode them
>> such the byte array will sort according to the magnitude of the value which
>> includes the sign and the floating point exponent.
>>
>> It's a very common problem :)
>>
>>
>> -- Lars
>>
>>
>>
>> ----- Original Message -----
>> From: David Koch <[EMAIL PROTECTED]>
>> To: [EMAIL PROTECTED]
>> Cc:
>> Sent: Thursday, November 29, 2012 3:00 PM
>> Subject: Re: Using doubles and longs as ordering row values
>>
>> Hello,
>>
>> I am having a similar issue, only I need to preserve the order of
>> qualifiers which are serialized signed longs - rather than row keys. The
>> latter is addressed by the orderly library which was mentioned above. Can
>> this library be re-used for my purpose? I imagine this is not an exotic
>> requirement so I am also interested in knowing how other people have solved
>> this problem.
>>
>> Thank you,
>>
>> /David
>>
>>
>> On Tue, Nov 6, 2012 at 6:07 AM, Jonathan Bishop <[EMAIL PROTECTED]
>>> wrote:
>>> Thanks Dave,
>>>
>>> That looks like what I need.
>>>
>>> Jon
>>>
>>>
>>> On Mon, Nov 5, 2012 at 4:27 PM, Dave Latham <[EMAIL PROTECTED]> wrote:
>>>
>>>> This fork looks a bit more up to date:
>>>> https://github.com/ndimiduk/orderly
>>>>
>>>> On Mon, Nov 5, 2012 at 4:26 PM, Dave Latham <[EMAIL PROTECTED]>
>> wrote:
>>>>> Here's a project to deal with this issue specifically.  I'm not sure
>> of
>>>>> it's status:
>>>>> https://github.com/conikeec/orderly
>>>>>
>>>>>
>>>>> On Mon, Nov 5, 2012 at 4:01 PM, lars hofhansl <[EMAIL PROTECTED]>
>>>> wrote:
>>>>>> Have a look at the lily library. It has code to encode Longs/Doubles
>>>> into
>>>>>> bytes such that resulting bytes sort as expected based on the
>> numbers.
>>>>>> -- Lars
>>>>>>
>>>>>>
>>>>>>
>>>>>> ________________________________
>>>>>>   From: Jonathan Bishop <[EMAIL PROTECTED]>
>>>>>> To: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
>>>>>> Sent: Monday, November 5, 2012 10:41 AM
>>>>>> Subject: Using doubles and longs as ordering row values
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> In my application my row values are doubles. I would like my scans
>> to
>>>>>> traverse the rows in order of increasing values.
>>>>>>
>>>>>> But if I simply use
>>>>>>
>>>>>> double d  = ....
>>>>>> byte[] row = Bytes.toBytes(d);
>>>>>>
>>>>>> I will get an ordering which is based on the byte values of doubles,
>>> not
>>>>>> on
>>>>>> the value of the doubles themselves.
>>>>>>
>>>>>> I see also that integer values have the same issue due to the first
>>> bit
>>>>>> being the sign bit. So negative values will come after positive
>>> values.
>>>>>> Any suggestions?
>>>>>>
>>>>>> Thanks,
>>>>>>
>>>>>> Jon
>>>>>>
>>>>>
>>
>
> 10mo. ANIVERSARIO DE LA CREACION DE LA UNIVERSIDAD DE LAS CIENCIAS INFORMATICAS...
> CONECTADOS AL FUTURO, CONECTADOS A LA REVOLUCION
>
> http://www.uci.cu
> http://www.facebook.com/universidad.uci
> http://www.flickr.com/photos/universidad_uci

--

Marcos Luis Ort�z Valmaseda
about.me/marcosortiz <http://about.me/marcosortiz>
@marcosluis2186 <http://twitter.com/marcosluis2186>

10mo. ANIVERSARIO DE LA CREACION DE LA UNIVERSIDAD DE LAS CIENCIAS INFORMATICAS...
CONECTADOS AL FUTURO, CONECTADOS A LA REVOLUCION

http://www.uci.cu
http://www.facebook.com/universidad.uci
http://www.flickr.com/photos/universidad_uci