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From Tyler Hobbs <ty...@datastax.com>
Subject Re: Highest and lowest valid values for UUIDs/TimeUUIDs
Date Tue, 24 Apr 2012 18:21:59 GMT
Oh, I just realized that you're asking about the lowest TimeUUID *overall*,
not just for a particular timestamp. Sorry.

The lowest possible TimeUUID is '00000000-0000-1000-8080-808080808080'.
The highest is 'ffffffff-ffff-1fff-bf7f-7f7f7f7f7f7f'.

On Tue, Apr 24, 2012 at 12:47 PM, Drew Kutcharian <drew@venarc.com> wrote:

> Thanks. So looking at the code, to get the lowest possible TimeUUID value
> using your function I should just call convert_time_to_uuid(0) ?
>
>
> On Apr 24, 2012, at 10:15 AM, Tyler Hobbs wrote:
>
> Yes, I have tested it.
>
> On Tue, Apr 24, 2012 at 12:08 PM, Drew Kutcharian <drew@venarc.com> wrote:
>
>> Thanks Tyler. So have you actually tried this with Cassandra?
>>
>>
>>
>> On Apr 24, 2012, at 5:44 AM, Tyler Hobbs wrote:
>>
>> At least for TimeUUIDs, this email I sent to client-dev@ a couple of
>> weeks ago should help to explain things:
>> http://www.mail-archive.com/client-dev@cassandra.apache.org/msg00125.html
>>
>> Looking at the linked pycassa code might be the most useful thing.
>>
>> On Tue, Apr 24, 2012 at 1:46 AM, Drew Kutcharian <drew@venarc.com> wrote:
>>
>>> Hi All,
>>>
>>> Considering that UUIDs are compared as numbers in Java [1], what are the
>>> lowest and highest possible values a valid UUID can have? How about
>>> TimeUUIDs?
>>>
>>> The reason I ask is that I would like to pick a "default" UUID value in
>>> a composite column definition like Composite(UUID1, UUID2) where UUID1 can
>>> be set to the default value if not supplied. In addition, it'd be nice if
>>> the "default" columns are always sorted before the rest of the columns.
>>>
>>> I was thinking of just doing "new UUID(Long.MAX_VALUE, Long.MAX_VALUE)"
>>> or "new UUID(Long.MIN_VALUE, Long.MIN_VALUE)" but not sure if that's going
>>> to cause other issues that I'm not aware of.
>>>
>>> Thanks,
>>>
>>> Drew
>>>
>>>
>>> [1] Here's the compareTo of java.util.UUID as a reference:
>>>
>>> public int compareTo(UUID val) {
>>>    // The ordering is intentionally set up so that the UUIDs
>>>    // can simply be numerically compared as two numbers
>>>    return (this.mostSigBits < val.mostSigBits ? -1 :
>>>            (this.mostSigBits > val.mostSigBits ? 1 :
>>>             (this.leastSigBits < val.leastSigBits ? -1 :
>>>              (this.leastSigBits > val.leastSigBits ? 1 :
>>>               0))));
>>> }
>>>
>>>
>>
>>
>> --
>> Tyler Hobbs
>> DataStax <http://datastax.com/>
>>
>>
>>
>
>
> --
> Tyler Hobbs
> DataStax <http://datastax.com/>
>
>
>


-- 
Tyler Hobbs
DataStax <http://datastax.com/>

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