Thanks Aaron, Yes I can put the column names without using the userId in the timeline row, and when I want to retrieve the row corresponding to that column name, I will attach the userId to get the row key.
Yes I'll store it as a long & I guess I'll have to write with a custom comparator type (ReversedIntegerType) to sort those longs in descending order. Regards Aditya On Sat, Feb 5, 2011 at 6:24 AM, aaron morton <aa...@thelastpickle.com> wrote: > IMHO If you know the time of the event use store the time as a long, rather > than a UUID. It will make it easier to get back to a > time and make it easier for you to compare columns. TimeUUIDS has a pseudo > random part as well as the time part, it could be set to a constant. By why > bother if you know the absolute time. > > I'm not sure what the ReminderCountOfThisUser is for, and as Sylvain says > there is no need for the user name if this is in a row just for the user. > > Hope that helps. > Aaron > > On 4 Feb 2011, at 01:32, Aditya Narayan wrote: > >> If I use : <TimestampOfDueTimeInFuture>: <UserId> : <ReminderCountOfThisUser> >> as key pattern for the rows of reminders, then I am storing the key, >> just as it is, as the column name and thus column values need not >> contain a link to the row containing the reminder details. >> >> I think UserId would be required along with timestamp in the key >> pattern to provide uniqueness to the key as there may be several >> reminders generated by users on the application, at the same time. >> >> But my question is about whether it is really advisable to even >> generate the keys like this pattern ... instead of going with >> timeuuids ? >> Are there are any downsides which I am not perhaps not aware of ? >> >> >> >> On Thu, Feb 3, 2011 at 5:43 PM, Sylvain Lebresne <sylv...@datastax.com> >> wrote: >>> On Thu, Feb 3, 2011 at 11:27 AM, Aditya Narayan <ady...@gmail.com> wrote: >>>> >>>> Hey all, >>>> >>>> I want to store some columns that are reminders to the users on my >>>> application, in time sorted order in a row(timeline row of the user). >>>> >>>> Would it be recommended to store these reminder columns in the >>>> timeline row with column names like: combination of timestamp(of time >>>> when the reminder gets due) + UserId+ Reminders Count of that user; >>>> Column Name= <TimestampOfDueTimeInFuture>: <UserId> : >>>> <ReminderCountOfThisUser> >>> >>> If you have one row by user (which is a good idea), why keep the UserId in >>> the column name ? >>> >>>> >>>> Then what comparator could I use to sort them in order of the their >>>> due time ? This comparator should be able to sort no. in descending >>>> order.(I guess ascii type would do the opposite order) (Reminders need >>>> to be sorted in the timeline in the order of their due time.) >>> >>> *The* solution is write a custom comparator. >>> Have a look at http://www.datastax.com/docs/0.7/data_model/column_families >>> and http://www.sodeso.nl/?p=421 for instance. >>> >>> As a side note, the fact that the comparator sort in ascending order when >>> you >>> need descending order would be that much of a problem, since you can always >>> do slice queries in reversed order. But even then, asciiType is not a very >>> satisfying solution as you would have to be careful about the padding of >>> your >>> timestamp for it to work correctly. So again, custom comparator is the way >>> to go. >>>> >>>> Basically I am trying to avoid 16 bytes long timeUUID first because >>>> they are too long and the above defined key pattern is guaranteeing me >>>> a unique key/Id for the reminder row always. >>>> >>>> >>>> Thanks >>>> Aditya Narayan >>> >>> -- >>> Sylvain > >
