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From Jonathan Shook <jsh...@gmail.com>
Subject Re: Perl/Thrift/Cassandra strangeness
Date Tue, 08 Jun 2010 17:20:49 GMT
Possible bug...

Using a slice range with the empty sentinel values, and a count of 1
sometimes yields 2 ColumnOrSuperColumns, sometimes 1.
The inconsistency had lead me to believe that the count was not
working, hence the additional confusion.

There was a particular key which returns exactly 2
ColumnOrSuperColumns. This happened repeatedly, even when other data
was inserted before or after. All of the other keys were returning the
expected 1 ColumnOrSuperColumn.

Once I added a 4th super column to the key in question, it started
behaving the same as the others, yielding exactly 1
ColumnOrSuperColumn.

here is the code: for the predicate:

        my $predicate = new Cassandra::SlicePredicate();
        my $slice_range = new Cassandra::SliceRange();
        $slice_range->{start} = '';
        $slice_range->{finish} = '';
        $slice_range->{reversed} = 1;
        $slice_range->{count} = 1;
        $predicate->{slice_range} = $slice_range;

The columns are in the right order (reversed), so I'll get what I need
by accessing only the first result in each slice. If I wanted to
iterate the returned list of slices, it would manifest as a bug in my
client.

(Cassandra 6.1/Thrift/Perl)


On Tue, Jun 8, 2010 at 11:18 AM, Jonathan Shook <jshook@gmail.com> wrote:
> I was misreading the result with the original slice range.
> I should have been expecting exactly 2 ColumnOrSuperColumns, which is
> what I got. I was erroneously expecting only 1.
>
> Thanks!
> Jonathan
>
>
> 2010/6/8 Ted Zlatanov <tzz@lifelogs.com>:
>> On Mon, 7 Jun 2010 17:20:56 -0500 Jonathan Shook <jshook@gmail.com> wrote:
>>
>> JS> The point is to get the "last" super-column.
>> ...
>> JS> Is the Perl Thrift client problematic, or is there something else that
>> JS> I am missing?
>>
>> Try Net::Cassandra::Easy; if it does what you want, look at the debug
>> output or trace the code to see how the predicate is specified so you
>> can duplicate that in your own code.
>>
>> In general yes, the Perl Thrift interface is problematic.  It's slow and
>> semantically inconsistent.
>>
>> Ted
>>
>>
>

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