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From 後藤 泰陽 <matope....@gmail.com>
Subject Re: Query first 1 columns for each partitioning keys in CQL?
Date Sat, 17 May 2014 06:53:55 GMT
Hello,

Thank you for your addressing.

But I consider LIMIT to be a keyword to limits result numbers from WHOLE results retrieved
by the SELECT statement.
The result with SELECT.. LIMIT is below. Unfortunately, This is not what I wanted.
I wante latest posts of each authors. (Now I doubt if CQL3 can't represent it)

> cqlsh:blog_test> create table posts(
>              ... author ascii,
>              ... created_at timeuuid,
>              ... entry text,
>              ... primary key(author,created_at)
>              ... )WITH CLUSTERING ORDER BY (created_at DESC);
> cqlsh:blog_test> 
> cqlsh:blog_test> insert into posts(author,created_at,entry) values ('john',minTimeuuid('2013-02-02
10:00+0000'),'This is an old entry by john');
> cqlsh:blog_test> insert into posts(author,created_at,entry) values ('john',minTimeuuid('2013-03-03
10:00+0000'),'This is a new entry by john');
> cqlsh:blog_test> insert into posts(author,created_at,entry) values ('mike',minTimeuuid('2013-02-02
10:00+0000'),'This is an old entry by mike');
> cqlsh:blog_test> insert into posts(author,created_at,entry) values ('mike',minTimeuuid('2013-03-03
10:00+0000'),'This is a new entry by mike');
> cqlsh:blog_test> select * from posts limit 2;
> 
>  author | created_at                           | entry
> --------+--------------------------------------+------------------------------
>    mike | 1c4d9000-83e9-11e2-8080-808080808080 |  This is a new entry by mike
>    mike | 4e52d000-6d1f-11e2-8080-808080808080 | This is an old entry by mike



2014/05/16 23:54、Jonathan Lacefield <jlacefield@datastax.com> のメール:

> Hello,
> 
>  Have you looked at using the CLUSTERING ORDER BY and LIMIT features of CQL3?
> 
>  These may help you achieve your goals.
> 
>   http://www.datastax.com/documentation/cql/3.1/cql/cql_reference/refClstrOrdr.html
>   http://www.datastax.com/documentation/cql/3.1/cql/cql_reference/select_r.html
> 
> Jonathan Lacefield
> Solutions Architect, DataStax
> (404) 822 3487
> 
> 
> 
> 
> 
> 
> On Fri, May 16, 2014 at 12:23 AM, Matope Ono <matope.ono@gmail.com> wrote:
> Hi, I'm modeling some queries in CQL3.
> 
> I'd like to query first 1 columns for each partitioning keys in CQL3.
> 
> For example:
> 
> create table posts(
> 	author ascii,
> 	created_at timeuuid,
> 	entry text,
> 	primary key(author,created_at)
> );
> insert into posts(author,created_at,entry) values ('john',minTimeuuid('2013-02-02 10:00+0000'),'This
is an old entry by john');
> insert into posts(author,created_at,entry) values ('john',minTimeuuid('2013-03-03 10:00+0000'),'This
is a new entry by john');
> insert into posts(author,created_at,entry) values ('mike',minTimeuuid('2013-02-02 10:00+0000'),'This
is an old entry by mike');
> insert into posts(author,created_at,entry) values ('mike',minTimeuuid('2013-03-03 10:00+0000'),'This
is a new entry by mike');
> 
> And I want results like below.
> 
> mike,1c4d9000-83e9-11e2-8080-808080808080,This is a new entry by mike
> john,1c4d9000-83e9-11e2-8080-808080808080,This is a new entry by john
> 
> I think that this is what "SELECT FIRST " statements did in CQL2.
> 
> The only way I came across in CQL3 is "retrieve whole records and drop manually",
> but it's obviously not efficient.
> 
> Could you please tell me more straightforward way in CQL3?
> 


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