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From "Sylvain Lebresne (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-7017) allow per-partition LIMIT clause in cql
Date Thu, 07 Apr 2016 09:43:25 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-7017?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15230004#comment-15230004
] 

Sylvain Lebresne commented on CASSANDRA-7017:
---------------------------------------------

We had just forgotten to add {{PER}} and {{PARTITION}} to the unreserved keywords in the grammar
which was breaking a test (that was using {{partition}} as a column name}}. I fixed that,
re-ran the tests, and everything was clear so committed. Thanks.

> allow per-partition LIMIT clause in cql
> ---------------------------------------
>
>                 Key: CASSANDRA-7017
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7017
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Jonathan Halliday
>            Assignee: Alex Petrov
>              Labels: cql
>             Fix For: 3.x
>
>         Attachments: 0001-Allow-per-partition-limit-in-SELECT-queries.patch, 0001-Allow-per-partition-limit-in-SELECT-queriesV2.patch,
0001-CASSANDRA-7017.patch
>
>
> somewhat related to static columns (#6561) and slicing (#4851), it is desirable to apply
a LIMIT on a per-partition rather than per-query basis, such as to retrieve the top (most
recent, etc) N clustered values for each partition key, e.g.
> -- for each league, keep a ranked list of users
> create table scores (league text, score int, player text, primary key(league, score,
player) );
> -- get the top 3 teams in each league:
> select * from scores staticlimit 3;
> this currently requires issuing one query per partition key, which is tedious if all
the key partition key values are known and impossible if they aren't.



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