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From Aaron Morton <aa...@thelastpickle.com>
Subject Re: LongType from user input
Date Thu, 30 Sep 2010 08:56:05 GMT
AFAIK indexes are still in dev. The only example is in the system_tests.py in the source tree.

Aaron

On 30 Sep 2010, at 20:10, Christian Decker <decker.christian@gmail.com> wrote:

> Apparently I have blanked the 0.7 completely out of my memory. I was trying to implement
application layer indices and ignored the fact that Cassandra 0.7 is implementing them by
default. I found ticket CASSANDRA-749 about the indices and am reading through the code right
now, but is there a higher level overview and a tutorial on how to get things started with
these indices (and maybe some inner workings)? This might actually solve all of my problems
I'm having right now :-)
> 
> Regards,
> Chris
> 
> 
> On Mon, Sep 27, 2010 at 3:45 AM, Aaron Morton <aaron@thelastpickle.com> wrote:
> The only thing I can think of is that values need to be in the correct byte format when
used in indexes in 0.7. Take a look at the types.py module in the pycassa client http://github.com/pycassa/pycassa
for an example of which values need to be byte packed. 
> 
> How is your pig function working against cassandra? Is it using the ColumnFamilyRecordReader?
. The code in the internal RowIterator for that class has an example calling the cluster to
get to the comparators.  
> 
> Aaron
> 
> 
> On 27 Sep, 2010,at 03:11 AM, Christian Decker <decker.christian@gmail.com> wrote:
> 
>> Hi Aaron,
>> 
>> what changes can I expect in the 0.7 release regarding Comparison and Parameters?
My problem is mainly that I want to take Strings from stdin (or Pig Scripts for that matter)
and convert them in such a way that they are interpreted correctly and converted to the corresponding
byte representation to use them in column names and keys.
>> 
>> Regards,
>> Chris
>> 
>> On Sun, Sep 26, 2010 at 5:20 AM, Aaron Morton <aaron@thelastpickle.com> wrote:
>> Things a changing in v0.7, the row keys are byte arrays.
>> 
>> Not sure I understand your other concerns. 
>> 
>> Aaron
>> 
>> 
>> On 25 Sep 2010, at 08:10, Christian Decker <decker.christian@gmail.com> wrote:
>> 
>> 
>>> Thanks for your quick answer, I think I'll use an affix to sort of cast the keys,
ranges and others from their textual representation (from Pig) to the desired byte representation,
since I just noticed that the keys for the rows themselfs are always UTF8 interpreted, and
since I want to make key-range as well as slice queries, I'll be better off this way I think.
I'll just add a 'L' for Long and 'U' for UUID (of any kind).
>>> Or is there a better way that I just can't see from my beginners angle? :-)thing
>>> 
>>> Regards,
>>> Chris
>>> 
>>> 
>>> On Fri, Sep 24, 2010 at 6:35 PM, Tyler Hobbs <tyler@riptano.com> wrote:
>>> Yes, you can use describe_keyspace() and then look through the results.  It's
a little ugly in 0.6, but it works
>>> 
>>> - Tyler
>>> 
>>> 
>>> 
>>> On Fri, Sep 24, 2010 at 11:25 AM, Christian Decker <decker.christian@gmail.com>
wrote:
>>> Well I'm writing a loading function for Pig, and as it happens I want to be able
to load slices from cassandra which are specified in the pig script (thus the input from stdin)
but the ColumnFamily from which to read the data is another parameter and some of the CFs
have UTF8, UUID, TimeUUID or Long types for their keys and columns, so simply converting everything
I get to an 8byte long would break compatibility with the others.
>>> Now thinking about it I attacked the whole problem in a weird way, since UUID
types won't work either.
>>> So let me change my question slightly, is there a way in 0.6 to detect the compareWith
type on a running cluster? That way I could convert it to the right type :D
>>> 
>>> Regards,
>>> Chris
>>> 
>>> 
>>> On Fri, Sep 24, 2010 at 6:09 PM, Tyler Hobbs <tyler@riptano.com> wrote:
>>> I'm not sure I understand why using this with multiple column families prevents
you from converting it.  Could you clarify this?
>>> 
>>> 
>>> 
>>> On Fri, Sep 24, 2010 at 10:56 AM, Christian Decker <decker.christian@gmail.com>
wrote:
>>> Hi all,
>>> 
>>> I'm having quite a dilemma with the CompareWith attribute. The Problem is that
I have numeric IDs that I'd like to use as row keys, only that I also have to offer a possibility
to let users input them from std input. Since I cannot ask my users to input an 8byte sequence
representing the ID they'd like, I was about to turn to UTF8, when I remembered that they
are compared lexicographically, so that 100 actually comes before 2, which kills key slices.
Also I cannot just code a converter in since this is supposed to be a used with multiple columnfamilies,
so just converting an integer read into 8bytes isn't going to work either.
>>> Any tricks for this one?
>>> 
>>> Regards,
>>> Chris
>>> 
>>> 
>>> 
>>> 
>> 
> 

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