It was our original intention on discussing this feature was to have
back-and-forth conversion from timestamps (we were modelling similar
functionality in Pycassa). It's lack of inclusion may have just been
an oversight. We will add this in Hector trunk shortly - thanks for
the complete code sample.
On Tue, Jan 4, 2011 at 10:06 PM, Roshan Dawrani <roshandawr...@gmail.com> wrote:
> Ok, found the solution - finally ! - by applying opposite of what
> createTime() does in TimeUUIDUtils. Ideally I would have preferred for this
> solution to come from Hector API, so I didn't have to be tied to the private
> createTime() implementation.
>
> ================================================================
> import java.util.UUID;
> import me.prettyprint.cassandra.utils.TimeUUIDUtils;
>
> public class TryHector {
> public static void main(String[] args) throws Exception {
> final long NUM_100NS_INTERVALS_SINCE_UUID_EPOCH =
> 0x01b21dd213814000L;
>
> UUID u1 = TimeUUIDUtils.getUniqueTimeUUIDinMillis();
> final long t1 = u1.timestamp();
>
> long tmp = (t1 - NUM_100NS_INTERVALS_SINCE_UUID_EPOCH) / 10000;
>
> UUID u2 = TimeUUIDUtils.getTimeUUID(tmp);
> long t2 = u2.timestamp();
>
> System.out.println(u2.equals(u1));
> System.out.println(t2 == t1);
> }
>
> }
> ================================================================
>
>
> On Wed, Jan 5, 2011 at 8:15 AM, Roshan Dawrani <roshandawr...@gmail.com>
> wrote:
>>
>> If I use com.eaio.uuid.UUID directly, then I am able to do what I need
>> (attached a Java program for the same), but unfortunately I need to deal
>> with java.util.UUID in my application and I don't have its equivalent
>> com.eaio.uuid.UUID at the point where I need the timestamp value.
>>
>> Any suggestion on how I can achieve the equivalent using Hector library's
>> TimeUUIDUtils?
>>
>> On Wed, Jan 5, 2011 at 7:21 AM, Roshan Dawrani <roshandawr...@gmail.com>
>> wrote:
>>>
>>> Hi Victor / Patricio,
>>>
>>> I have been using Hector library's TimeUUIDUtils. I also just looked at
>>> TimeUUIDUtilsTest also but didn't find anything similar being tested there.
>>>
>>> Here is what I am trying and it's not working - I am creating a Time
>>> UUID, extracting its timestamp value and with that I create another Time
>>> UUID and I am expecting both time UUIDs to have the same timestamp() value -
>>> am I doing / expecting something wrong here?:
>>>
>>> =======================================================
>>> import java.util.UUID;
>>> import me.prettyprint.cassandra.utils.TimeUUIDUtils;
>>>
>>> public class TryHector {
>>> public static void main(String[] args) throws Exception {
>>> UUID someUUID = TimeUUIDUtils.getUniqueTimeUUIDinMillis();
>>> long timestamp1 = someUUID.timestamp();
>>>
>>> UUID otherUUID = TimeUUIDUtils.getTimeUUID(timestamp1);
>>> long timestamp2 = otherUUID.timestamp();
>>>
>>> System.out.println(timestamp1);
>>> System.out.println(timestamp2);
>>> }
>>> }
>>> =======================================================
>>>
>>> I have to create the timestamp() equivalent of my time UUIDs so I can
>>> send it to my UI client, for which it will be simpler to compare "long"
>>> timestamp than comparing UUIDs. Then for the "long" timestamp chosen by the
>>> client, I need to re-create the equivalent time UUID and go and filter the
>>> data from Cassandra database.
>>>
>>> --
>>> Roshan
>>> Blog: http://roshandawrani.wordpress.com/
>>> Twitter: @roshandawrani
>>> Skype: roshandawrani
>>>
>>> On Wed, Jan 5, 2011 at 1:32 AM, Victor Kabdebon
>>> <victor.kabde...@gmail.com> wrote:
>>>>
>>>> Hi Roshan,
>>>> Sorry I misunderstood your problem.It is weird that it doesn't work, it
>>>> works for me...
>>>> As Patricio pointed out use hector "standard" way of creating TimeUUID
>>>> and tell us if it still doesn't work.
>>>> Maybe you can paste here some of the code you use to query your columns
>>>> too.
>>>>
>>>> Victor K.
>>>> http://www.voxnucleus.fr
>>>>
>>>> 2011/1/4 Patricio Echagüe <patric...@gmail.com>
>>>>>
>>>>> In Hector framework, take a look at TimeUUIDUtils.java
>>>>>
>>>>> You can create a UUID using TimeUUIDUtils.getTimeUUID(long time); or
>>>>> TimeUUIDUtils.getTimeUUID(ClockResolution clock)
>>>>>
>>>>> and later on, TimeUUIDUtils.getTimeFromUUID(..) or just
>>>>> UUID.timestamp();
>>>>>
>>>>> There are some example in TimeUUIDUtilsTest.java
>>>>>
>>>>> Let me know if it helps.
>>>>>
>>>>>
>>>>>
>>>>> On Tue, Jan 4, 2011 at 10:27 AM, Roshan Dawrani
>>>>> <roshandawr...@gmail.com> wrote:
>>>>>>
>>>>>> Hello Victor,
>>>>>>
>>>>>> It is actually not that I need the 2 UUIDs to be exactly same - they
>>>>>> need to be same timestamp wise.
>>>>>>
>>>>>> So, what I need is to extract the timestamp portion from a time UUID
>>>>>> (say, U1) and then later in the cycle, use the same long timestamp value
>>>>>> to
>>>>>> re-create a UUID (say, U2) that is equivalent of the previous one in
>>>>>> terms
>>>>>> of its timestamp portion - i.e., I should be able to give this U2 and
>>>>>> filter
>>>>>> the data from a column family - and it should be same as if I had used
>>>>>> the
>>>>>> original UUID U1.
>>>>>>
>>>>>> Does it make any more sense than before? Any way I can do that?
>>>>>>
>>>>>> rgds,
>>>>>> Roshan
>>>>>>
>>>>>> On Tue, Jan 4, 2011 at 11:46 PM, Victor Kabdebon
>>>>>> <victor.kabde...@gmail.com> wrote:
>>>>>>>
>>>>>>> Hello Roshan,
>>>>>>> Well it is normal to do not be able to get the exact same UUID from a
>>>>>>> timestamp, it is its purpose.
>>>>>>> When you create an UUID you have in fact two information : random 64
>>>>>>> bits number - 64 bits timestamp. You put that together and you have your
>>>>>>> uuid.
>>>>>>> .
>>>>>>> So unless you save your random number two UUID for the same milli( or
>>>>>>> micro) second are different.
>>>>>>> Best regards,
>>>>>>> Victor K.
>>>>>>> http://www.voxnucleus.fr
>>>>>>>
>>>>>>> 2011/1/4 Roshan Dawrani <roshandawr...@gmail.com>
>>>>>>>>
>>>>>>>> Hi,
>>>>>>>> I am having a little difficulty converting a time UUID to its
>>>>>>>> timestamp equivalent and back. Can someone please help?
>>>>>>>>
>>>>>>>> Here is what I am trying. Is it not the right way to do it?
>>>>>>>>
>>>>>>>> ===========================================================
>>>>>>>> UUID someUUID = TimeUUIDUtils.getUniqueTimeUUIDinMillis();
>>>>>>>>
>>>>>>>> long time = someUUID.timestamp(); /* convery from UUID to a
>>>>>>>> long timestamp */
>>>>>>>> UUID otherUUID = TimeUUIDUtils.getTimeUUID(time); /* do the
>>>>>>>> reverse and get back the UUID from timestamp */
>>>>>>>>
>>>>>>>> System.out.println(someUUID); /* someUUID and otherUUID
>>>>>>>> should be same, but are different */
>>>>>>>> System.out.println(otherUUID);
>>>>>>>> ===========================================================
>>>>>>>>
>>>>>>>> --
>>>>>>>> Roshan
>>>>>>>> Blog: http://roshandawrani.wordpress.com/
>>>>>>>> Twitter: @roshandawrani
>>>>>>>> Skype: roshandawrani
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Roshan
>>>>>> Blog: http://roshandawrani.wordpress.com/
>>>>>> Twitter: @roshandawrani
>>>>>> Skype: roshandawrani
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Patricio.-
>>>>
>>>
>
>
>
> --
> Roshan
> Blog: http://roshandawrani.wordpress.com/
> Twitter: @roshandawrani
> Skype: roshandawrani
>
>
