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From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Perl/Thrift/Cassandra strangeness
Date Tue, 08 Jun 2010 02:31:13 GMT
you'll get "column name must not be empty" if you specify a list of
columns, rather than a slicepredicate.

it sounds like you might be trying to specify slices, of a set of
supercolumns?  you can't do that; you can specify slices of a single
columnparent.  if that is the CF then you get multiple supercolumns
back, if it is a SC you get subcolumns from just that SC.

On Mon, Jun 7, 2010 at 3:20 PM, Jonathan Shook <jshook@gmail.com> wrote:
> I have a structure like this:
>
> CF:"Status"
> {
>  Row("Component42")
>  {
>    SuperColumn(1275948636203) (epoch millis)
>    {
>      sub columns...
>    }
>  }
> }
>
> The supercolumns are dropped in periodically by system A, which is using Hector.
> System B uses a lightweight perl/Thrift client to reduce process
> overhead. (It gets called as a process frequently)
> This will go away at some point, but for now it is the de-facto means
> for integrating the two systems.
>
> According to the API docs, under get_range_slices, "The empty string
> ("") can be used as a sentinel value to get the first/last existing
> key (or first/last column in the column predicate parameter)"
> This seems to conflict directly with the error message that I am
> getting: "column name must not be empty", which ISA
> Cassandra::InvalidRequestException.
>
> The point is to get the "last" super-column.
>
> I've also tried to set the predicate's slice_range for "all columns,
> reversed, limit 1" but it simply returns multiple super columns.
>
> Is the Perl Thrift client problematic, or is there something else that
> I am missing?
>



-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of Riptano, the source for professional Cassandra support
http://riptano.com

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