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From Wei Zhu <wz1...@yahoo.com>
Subject Re: Create CF with composite column through CQL 3
Date Wed, 31 Oct 2012 21:02:04 GMT
Thanks Tristan and Sylvain, it all makes sense now. 

One follow up question regarding the composite column. It seems that for the where clause
I can only restrict the query on the first composite column (friend_id, in my case). I understand
it's determined by the underlining row storage structure. 
Is any plan to improve that to be able to search on the other composite columns if I don't
care about the performance.

cqlsh:demo> select * from friends where source = 7;
Bad Request: PRIMARY KEY part source cannot be restricted (preceding part status is either
not restricted or by a non-EQ relation)


Thanks.
-Wei


________________________________
 From: Tristan Seligmann <mithrandi@mithrandi.net>
To: user@cassandra.apache.org; Wei Zhu <wz1975@yahoo.com> 
Sent: Wednesday, October 31, 2012 10:47 AM
Subject: Re: Create CF with composite column through CQL 3
 
On Wed, Oct 31, 2012 at 7:14 PM, Wei Zhu <wz1975@yahoo.com> wrote:
> I try to use CQL3 to create CF with composite columns,
>
>  CREATE TABLE Friends (
>          ...     user_id bigint,
>          ...     friend_id bigint,
>          ...     status int,
>          ...     source int,
>          ...     created timestamp,
>          ...     lastupdated timestamp,
>          ...     PRIMARY KEY (user_id, friend_id, status, source)
>          ... );
>
>
> When I check it with cli, the composite type is a bit odd, why it's defined
> as Long, Int32, Int32, UTF8, is it supposed to be Long, Long, Int32, Int32?

The first component of the PRIMARY KEY (user_id) is the row key:

>       Key Validation Class: org.apache.cassandra.db.marshal.LongType

The rest of the components (friend_id, status, source) are part of the
column name:

>       Columns sorted by: org.apache.cassandra.db.marshal.CompositeType(
> org.apache.cassandra.db.marshal.LongType,
> org.apache.cassandra.db.marshal.Int32Type,
> org.apache.cassandra.db.marshal.Int32Type,

and the final component of of the column name is the "CQL-level" column name:

> org.apache.cassandra.db.marshal.UTF8Type)

In this case, it will be "created" or "lastupdated" as those are the
only columns not part of the PRIMARY KEY.
-- 
mithrandi, i Ainil en-Balandor, a faer Ambar
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