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From Martin Koch <...@issuu.com>
Subject Re: Option for ordering columns by timestamp in CF
Date Sat, 13 Oct 2012 15:20:29 GMT
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 <btoddb@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 <derek@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 <ertiop93@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 <tyler@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 <ertiop93@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 <
> aaron@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
> >
>

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