On 8/13/10 10:01 AM, Sylvain Lebresne wrote:
True, it's more annoying to do because you need to construct a UUID whose time
part is what you need and the rest of the bytes are zeros (excepted for the
version bit that should be one for the UUID to be valid if I remember
correctly).
And usually, UUID generator don't give you that, you'll have to 'do it
yourself',
which is annoying (but not very hard if you look a UUID version 1 layout).
--
Sylvain
On Fri, Aug 13, 2010 at 6:54 PM, Mark<[email protected]> wrote:
On 8/13/10 9:38 AM, Sylvain Lebresne wrote:
As long as time sorting is involved, you'll the same ordering if you
use Epoch/Long
or TimeUUID. The difference is between the ties. If when you insert
two values at
the exact same time, you want to have only one stay, then you want
LongType.
If however you don't want to merge such inserts, then you want TimeUUID
since
they assure you that even if generated at the exact same time, the key
will be different
(plus if your UUID generator is not too bad, it will give you better
precision than the
epoch/long one).
--
Sylvain
On Fri, Aug 13, 2010 at 6:32 PM, Mark<[email protected]> wrote:
I'm a little confused on when I should be using TimeUUID vs Epoch/Long
when
I want columns ordered by time. I know it sounds strange and the obvious
choice should be TimeUUID but I'm not sure why that would be preferred
over
just using the Epoch stamp?
The pretty much seem to accomplish the same thing however when using
Epoch I
can easily use a start/end range for querying across times. Can this be
accomplished using TimeUUID?
Would someone also explain how TimeUUID is actually sorted? Im confused
on
how its actually compared. Thanks!
So long story short you can give a start/end range when using TimeUUID?
For example I am storing a bunch of records keyed by the current date
"20100813". Each column is a TimeUUID. If I wanted to get all the columns
that between some arbitrary time.. say 6am - 9am I can get that?
Using Long I can just use a start of "1281704400000000" and a finish of
"1281715200000000" but Im unsure of how to represent that as a TimeUUID.
Thanks for the help. Im using UUID version 1 so Ill have to look into
how this would be accomplished. Im using the SimpleUUID ruby gem so if
anyone knows how this is done please chime in :)
