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From "Kevin" <>
Subject RE: When does it make sense to use TimeUUID?
Date Wed, 15 Jun 2011 00:43:21 GMT
Correction. TimeUUID comparisons FIRST compare the  time-based portion, then
go on to the other portion.


From: Sameer Farooqui [] 
Sent: Tuesday, June 14, 2011 8:16 PM
Subject: When does it make sense to use TimeUUID?


I would like to store some timestamped user info in a Column Family with the
usernames as the row key and different timestamps as column names. Each user
might have a thousand timestamped data.


I understand that the ver 1 UUIDs that Cassandra combines the MAC address of
the computer generating the UUID with the number of 100-nanosecond intervals
since the beginning of the Gregorian calendar.


So, if user1 had data stored for an event at Jan 30, 2011/2:15pm and user2
had an event at the exact same time, the data could potentially be stored in
different column names? So, I would have to know the MAC of the generating
computer in order to do a column slice, right? 


When does it make sense to use TimeUUID vs just a time string like
20110130141500 and comparator type UTF8?


- Sameer

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