@B Todd Burruss: Regarding the use cases, I think they are pretty common. At least I see its usages very frequently in my project. Lets say when the application needs to store a timeline of bookmark activity by a user on certain items then if I could store the activity data containing columns(with concerned item id as column name) & get it ordered by timestamp then I could also fetch from that row whether or not a particular item was bookmarked by user. Ordering columns by time is a very common requirement in any application therefore if such a mechanism is provided by cassandra, it would be really useful & convenient to app developers.
On Sat, Oct 13, 2012 at 8:50 PM, Martin Koch <m...@issuu.com> wrote: > One example could be to identify when a row was last updated. For example, > if I have a column family for storing users, the row key is a user ID and > the columns are values for that user, e.g. natural column names would be > "firstName", "lastName", "address", etc; column names don't naturally > include a date here. > > Sorting the coulmns by timestamp and picking the last would allow me to > know when the row was last modified. (I could manually maintain a 'last > modified' column as well, I know, but just coming up with a use case :). > > /Martin Koch > > > On Fri, Oct 12, 2012 at 11:39 PM, B. Todd Burruss <bto...@gmail.com>wrote: > >> trying to think of a use case where you would want to order by >> timestamp, and also have unique column names for direct access. >> >> not really trying to challenge the use case, but you can get ordering >> by timestamp and still maintain a "name" for the column using >> composites. if the first component of the composite is a timestamp, >> then you can order on it. when retrieved you will could have a "name" >> in the second component .. and have dupes as long as the timestamp is >> unique (use TimeUUID) >> >> >> On Fri, Oct 12, 2012 at 7:20 AM, Derek Williams <de...@fyrie.net> wrote: >> > You probably already know this but I'm pretty sure it wouldn't be a >> trivial >> > change, since to efficiently lookup a column by name requires the >> columns to >> > be ordered by name. A separate index would be needed in order to provide >> > lookup by column name if the row was sorted by timestamp (which is the >> way >> > Redis implements it's sorted set). >> > >> > >> > On Fri, Oct 12, 2012 at 12:13 AM, Ertio Lew <ertio...@gmail.com> wrote: >> >> >> >> "Make column timestamps optional"- kidding me, right ?:) I do >> understand >> >> that this wont be possible as then cassandra wont be able to >> distinguish the >> >> latest among several copies of same column. I dont mean that. I just >> want >> >> the while ordering the columns, Cassandra(in an optional mode per CF) >> should >> >> not look at column names(they will exist though but for retrieval >> purposes >> >> not for ordering) but instead Cassandra would order the columns by >> looking >> >> at the timestamp values(timestamps would exist!). So the change would >> be >> >> just to provide a mode in which cassandra, while ordering, uses >> timestamps >> >> instead of column names. >> >> >> >> >> >> On Fri, Oct 12, 2012 at 2:26 AM, Tyler Hobbs <ty...@datastax.com> >> wrote: >> >>> >> >>> Without thinking too deeply about it, this is basically equivalent to >> >>> disabling timestamps for a column family and using timestamps for >> column >> >>> names, though in a very indirect (and potentially confusing) manner. >> So, if >> >>> you want to open a ticket, I would suggest framing it as "make column >> >>> timestamps optional". >> >>> >> >>> >> >>> On Wed, Oct 10, 2012 at 4:44 AM, Ertio Lew <ertio...@gmail.com> >> wrote: >> >>>> >> >>>> I think Cassandra should provide an configurable option on per column >> >>>> family basis to do columns sorting by time-stamp rather than column >> names. >> >>>> This would be really helpful to maintain time-sorted columns without >> using >> >>>> up the column name as time-stamps which might otherwise be used to >> store >> >>>> most relevant column names useful for retrievals. Very frequently we >> need to >> >>>> store data sorted in time order. Therefore I think this may be a very >> >>>> general requirement & not specific to just my use-case alone. >> >>>> >> >>>> Does it makes sense to create an issue for this ? >> >>>> >> >>>> >> >>>> >> >>>> >> >>>> On Fri, Mar 25, 2011 at 2:38 AM, aaron morton < >> aa...@thelastpickle.com> >> >>>> wrote: >> >>>>> >> >>>>> If you mean order by the column timestamp (as passed by the client) >> >>>>> that it not possible. >> >>>>> >> >>>>> Can you use your own timestamps as the column name and store them as >> >>>>> long values ? >> >>>>> >> >>>>> Aaron >> >>>>> >> >>>>> On 25 Mar 2011, at 09:30, Narendra Sharma wrote: >> >>>>> >> >>>>> > Cassandra 0.7.4 >> >>>>> > Column names in my CF are of type byte[] but I want to order >> columns >> >>>>> > by timestamp. What is the best way to achieve this? Does it make >> sense for >> >>>>> > Cassandra to support ordering of columns by timestamp as option >> for a column >> >>>>> > family irrespective of the column name type? >> >>>>> > >> >>>>> > Thanks, >> >>>>> > Naren >> >>>>> >> >>>> >> >>> >> >>> >> >>> >> >>> -- >> >>> Tyler Hobbs >> >>> DataStax >> >>> >> >> >> > >> > >> > >> > -- >> > Derek Williams >> > >> > >
