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From "Avi Kivity (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-14311) Allow Token-Aware drivers for range scans
Date Wed, 14 Mar 2018 08:00:00 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-14311?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16398201#comment-16398201
] 

Avi Kivity commented on CASSANDRA-14311:
----------------------------------------

{quote}Interesting. If the page border spans to another token, you'd still want to fill the
whole page, wouldn't you? I assume so.
{quote}
 

You could, but you could also return a short page. In any case node-crossings are rare, so
it doesn't matter much.

 
{quote}Doesn't the driver already have an option to choose the next host in the ring if it
determines the paging state is beyond the original coordinator's boundary?
{quote}
 

paging_state is opaque, the driver cannot interpret it.

 

> Allow Token-Aware drivers for range scans
> -----------------------------------------
>
>                 Key: CASSANDRA-14311
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-14311
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Coordination
>            Reporter: Avi Kivity
>            Priority: Major
>
> Currently, range scans are not token aware. This means that an extra hop is needed for
most requests. Since range scans are usually data intensive, this causes significant extra
traffic.
>  
> Token awareness could be enabled by having the coordinator return the token for the next
(still unread) row in the response, so the driver can select a next coordinator that owns
this row.



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