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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 12:44:29 GMT
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/>

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