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From "Christoph Tavan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-4176) Support for sharding wide rows in CQL 3.0
Date Mon, 04 Jun 2012 08:28:23 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4176?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13288413#comment-13288413
] 

Christoph Tavan commented on CASSANDRA-4176:
--------------------------------------------

I think the suggestion to discuss sharding and composite row keys/values in a different issue
is good.

If we wanna have event more specific/dedicated support for sharding, a different syntax idea
for (borrowed from [MySQL|http://dev.mysql.com/doc/refman/5.1/en/create-table.html]) might
be:

{code}
CREATE TABLE timeline (
    user_id varchar,
    tweet_id uuid,
    author varchar,
    body varchar,
    PRIMARY KEY (user_id, tweet_id)
) PARTITION BY HASH(user_id, DAY(tweet_id)) PARTITIONS 10;
{code}

It would read very straightforward IMO, but maybe that's already too high-level? 
                
> Support for sharding wide rows in CQL 3.0
> -----------------------------------------
>
>                 Key: CASSANDRA-4176
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4176
>             Project: Cassandra
>          Issue Type: Sub-task
>          Components: API
>            Reporter: Nick Bailey
>             Fix For: 1.1.2
>
>
> CQL 3.0 currently has support for defining wide rows by declaring a composite primary
key. For example:
> {noformat}
> CREATE TABLE timeline (
>     user_id varchar,
>     tweet_id uuid,
>     author varchar,
>     body varchar,
>     PRIMARY KEY (user_id, tweet_id)
> );
> {noformat}
> It would also be useful to manage sharding a wide row through the cql schema. This would
require being able to split up the actual row key in the schema definition. In the above example
you might want to make the row key a combination of user_id and day_of_tweet, in order to
shard timelines by day. This might look something like:
> {noformat}
> CREATE TABLE timeline (
>     user_id varchar,
>     day_of_tweet date,
>     tweet_id uuid,
>     author varchar,
>     body varchar,
>     PRIMARY KEY (user_id REQUIRED, day_of_tweet REQUIRED, tweet_id)
> );
> {noformat}
> Thats probably a terrible attempt at how to structure that in CQL. But I think I've gotten
the point across. I tagged this for cql 3.0, but I'm honestly not sure how much work it might
be. As far as I know built in support for composite keys is limited.

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