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From Sylvain Lebresne <sylv...@datastax.com>
Subject Re: Issue with ALLOW FILTERING
Date Wed, 06 Aug 2014 08:03:43 GMT
On Wed, Aug 6, 2014 at 9:41 AM, Jens Rantil <jens.rantil@tink.se> wrote

>
> I'm struggling to see any reason for it not being supported.
>

The time to implement it, plus a bunch of internal implementation reasons
that makes it not as trivial to support as you seem to suggest it is (of
course, this is open source, you are welcome to have a look if that's a
particular itch you want to scratch; there is even a JIRA ticket:
https://issues.apache.org/jira/browse/CASSANDRA-6377).


>
> Or is it considered implementation specific under what circumstances ALLOW
> FILTERING can be used?
>

Currently, it kind of is. ALLOW FILTERING allows to execute "some" queries
that couldn't be otherwise, but not everything. Again, things that are not
supported are not mainly for implementation reasons, nothing more, and that
may/will change in the future. That said, I'm not saying documentation
cannot be improved (though I'm not sure having the doc saying "this doesn't
work" would be a lot more helpful than trying it and having the
implementation saying "this doesn't work").

--
Sylvain


>
> Thanks,
> Jens
>
>
> On Tue, Aug 5, 2014 at 8:11 PM, Sávio S. Teles de Oliveira <
> savio.teles@cuia.com.br> wrote:
>
>> You need to create an index on attribute *c.*
>>
>>
>> 2014-08-05 9:24 GMT-03:00 Jens Rantil <jens.rantil@tink.se>:
>>
>> Hi,
>>>
>>> I'm having an issue with ALLOW FILTERING with Cassandra 2.0.8. See a
>>> minimal example here:
>>> https://gist.github.com/JensRantil/ec43622c26acb56e5bc9
>>>
>>> I expect the second last to fail, but the last query to return a single
>>> row. In particular I expect the last SELECT to first select using the
>>> clustering primary id and then do filtering.
>>>
>>> I've been reading
>>> https://cassandra.apache.org/doc/cql3/CQL.html#selectStmt "ALLOW
>>> FILTERING" and can't wrap my head around why this won't work.
>>>
>>> Could anyone clarify this for me?
>>>
>>> Thanks,
>>> Jens
>>>
>>
>>
>>
>> --
>> Atenciosamente,
>> Sávio S. Teles de Oliveira
>> voice: +55 62 9136 6996
>> http://br.linkedin.com/in/savioteles
>>  Mestrando em Ciências da Computação - UFG
>> Arquiteto de Software
>> CUIA Internet Brasil
>>
>
>

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