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Posted to user@cassandra.apache.org by Jens Rantil <je...@tink.se> on 2014/08/05 14:24:18 UTC
Issue with ALLOW FILTERING
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
Re: Issue with ALLOW FILTERING
Posted by Robert Coli <rc...@eventbrite.com>.
On Wed, Aug 6, 2014 at 1:46 AM, Jens Rantil <je...@tink.se> wrote:
> Your answer was what I was hoping for - that means it's not impossible to
> solve ;)
>
> I'll keep an eye on the issue and in case I have the time I will dig into
> some code.
>
Just have to mention here that :
"ALLOW FILTERING should be renamed PROBABLY TIMEOUT in order to properly
describe its typical performance."
If you find yourself having to use ALLOW FILTERING, it is possible you are
Doing It Wrong.. :D
=Rob
Re: Issue with ALLOW FILTERING
Posted by Jens Rantil <je...@tink.se>.
Sylvain,
Your answer was what I was hoping for - that means it's not impossible to
solve ;)
I'll keep an eye on the issue and in case I have the time I will dig into
some code.
Thanks,
Jens
On Wed, Aug 6, 2014 at 10:03 AM, Sylvain Lebresne <sy...@datastax.com>
wrote:
> On Wed, Aug 6, 2014 at 9:41 AM, Jens Rantil <je...@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 <je...@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
>>>
>>
>>
>
Re: Issue with ALLOW FILTERING
Posted by Sylvain Lebresne <sy...@datastax.com>.
On Wed, Aug 6, 2014 at 9:41 AM, Jens Rantil <je...@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 <je...@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
>>
>
>
Re: Issue with ALLOW FILTERING
Posted by Jens Rantil <je...@tink.se>.
Hi Sávio,
I am really surprised by this. Could anyone explain why ALLOW FILTERING
only is allowed when using secondary index and not together with a PRIMARY
KEY? I'm struggling to see any reason for it not being supported.
Also, I don't believe the CQL specification makes it entirely clear that
only secondary indexes are supported. Or is it considered implementation
specific under what circumstances ALLOW FILTERING can be used?
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 <je...@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
>
Re: Issue with ALLOW FILTERING
Posted by "Sávio S. Teles de Oliveira" <sa...@cuia.com.br>.
You need to create an index on attribute *c.*
2014-08-05 9:24 GMT-03:00 Jens Rantil <je...@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