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From David Savage <davemssav...@gmail.com>
Subject Re: CQL Select Map using an IN relationship
Date Thu, 13 Mar 2014 15:27:51 GMT
Great that works, thx! I probably would have never found that...

It now makes me wonder in general when to use PRIMARY KEY (key1, key2) or
PRIMARY KEY ((key1, key2)), any examples would be welcome if you have the
time.

Kind regards,

Dave


On Thu, Mar 13, 2014 at 2:56 PM, Laing, Michael
<michael.laing@nytimes.com>wrote:

> Create your table like this and it will work:
>
> CREATE TABLE test.documents (group text,id bigint,data
> map<text,text>,PRIMARY KEY ((group, id)));
>
> The extra parens catenate 'group' and 'id' into the partition key - IN
> will work on the last component of a partition key.
>
> ml
>
>
> On Thu, Mar 13, 2014 at 10:40 AM, David Savage <davemssavage@gmail.com>wrote:
>
>> Nope, upgraded to 2.0.5 and still get the same problem, I actually
>> simplified the problem a little in my first post, there's a composite
>> primary key involved as I need to partition ids into groups
>>
>> So the full CQL statements are:
>>
>> CREATE KEYSPACE test WITH replication = {'class':'SimpleStrategy',
>> 'replication_factor':3};
>>
>>
>> CREATE TABLE test.documents (group text,id bigint,data
>> map<text,text>,PRIMARY KEY (group, id));
>>
>>
>> INSERT INTO test.documents(id,group,data) VALUES (0,'test',{'count':'0'});
>>
>> INSERT INTO test.documents(id,group,data) VALUES (1,'test',{'count':'1'});
>>
>> INSERT INTO test.documents(id,group,data) VALUES (2,'test',{'count':'2'});
>>
>>
>> SELECT id,data FROM test.documents WHERE group='test' AND id IN (0,1,2);
>>
>>
>> Thanks for your help.
>>
>>
>> Kind regards,
>>
>>
>> /Dave
>>
>>
>> On Thu, Mar 13, 2014 at 2:00 PM, David Savage <davemssavage@gmail.com>wrote:
>>
>>> Hmmm that maybe the problem, I'm currently testing with 2.0.2 which got
>>> dragged in by the cassandra unit library I'm using for testing [1] I will
>>> try to fix my build dependencies and retry, thx.
>>>
>>> /Dave
>>>
>>> [1] https://github.com/jsevellec/cassandra-unit
>>>
>>>
>>> On Thu, Mar 13, 2014 at 1:56 PM, Laing, Michael <
>>> michael.laing@nytimes.com> wrote:
>>>
>>>> I have no problem doing this w 2.0.5 - what version of C* are you
>>>> using? Or maybe I don't understand your data model... attach 'creates' if
>>>> you don't mind.
>>>>
>>>> ml
>>>>
>>>>
>>>> On Thu, Mar 13, 2014 at 9:24 AM, David Savage <davemssavage@gmail.com>wrote:
>>>>
>>>>> Hi Peter,
>>>>>
>>>>> Thanks for the help, unfortunately I'm not sure that's the problem,
>>>>> the id is the primary key on the documents table and the timestamp is
>>>>> the primary key on the eventlog table
>>>>>
>>>>> Kind regards,
>>>>>
>>>>>
>>>>> Dave
>>>>>
>>>>> On Thursday, 13 March 2014, Peter Lin <woolfel@gmail.com> wrote:
>>>>>
>>>>>>
>>>>>> it's not clear to me if your "id" column is the KEY or just a regular
>>>>>> column with secondary index.
>>>>>>
>>>>>> queries that have IN on non primary key columns isn't supported yet.
>>>>>> not sure if that answers your question.
>>>>>>
>>>>>>
>>>>>> On Thu, Mar 13, 2014 at 7:12 AM, David Savage <davemssavage@gmail.com
>>>>>> > wrote:
>>>>>>
>>>>>>> Hi there,
>>>>>>>
>>>>>>> I'm experimenting using cassandra and have run across an error
>>>>>>> message which I need a little more information on.
>>>>>>>
>>>>>>> The use case I'm experimenting with is a series of document updates
>>>>>>> (documents being an arbitrary map of key value pairs), I would
like to find
>>>>>>> the latest document updates after a specified time period. I
don't want to
>>>>>>> store many copies of the documents (one per update) as the updates
are
>>>>>>> often only to single keys in the map so that would involve a
lot of
>>>>>>> duplicated data.
>>>>>>>
>>>>>>> The solution I've found that seems to fit best in terms of
>>>>>>> performance is to have two tables.
>>>>>>>
>>>>>>> One that has an event log of timeuuid -> docid and a second
that
>>>>>>> stores the documents themselves stored by docid -> map<string,
string>. I
>>>>>>> then run two queries, one to select ids that have changed after
a certain
>>>>>>> time:
>>>>>>>
>>>>>>> SELECT id FROM eventlog WHERE timestamp>=minTimeuuid($minimumTime)
>>>>>>>
>>>>>>> and then a second to select the actual documents themselves
>>>>>>>
>>>>>>> SELECT id, data FROM documents WHERE id IN (0, 1, 2, 3, 4, 5,
6, 7...)
>>>>>>>
>>>>>>> However this then explodes on query with the error message:
>>>>>>>
>>>>>>> "Cannot restrict PRIMARY KEY part id by IN relation as a collection
>>>>>>> is selected by the query"
>>>>>>>
>>>>>>> Detective work lead me to these lines in
>>>>>>> org.apache.cassandra.cql3.statementsSelectStatement:
>>>>>>>
>>>>>>>                     // We only support IN for the last name and
for
>>>>>>> compact storage so far
>>>>>>>                     // TODO: #3885 allows us to extend to non
>>>>>>> compact as well, but that remains to be done
>>>>>>>                     if (i != stmt.columnRestrictions.length -
1)
>>>>>>>                         throw new
>>>>>>> InvalidRequestException(String.format("PRIMARY KEY part %s cannot
be
>>>>>>> restricted by IN relation", cname));
>>>>>>>                     else if (stmt.selectACollection())
>>>>>>>                         throw new
>>>>>>> InvalidRequestException(String.format("Cannot restrict PRIMARY
KEY part %s
>>>>>>> by IN relation as a collection is selected by the query", cname));
>>>>>>>
>>>>>>> It seems like #3885 will allow support for the first IF block
above,
>>>>>>> but I don't think it will allow the second, am I correct?
>>>>>>>
>>>>>>> Any pointers on how I can work around this would be greatly
>>>>>>> appreciated.
>>>>>>>
>>>>>>> Kind regards,
>>>>>>>
>>>>>>> Dave
>>>>>>>
>>>>>>
>>>>>>
>>>>
>>>
>>
>

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