Mailing-List: contact commits-help@cassandra.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@cassandra.apache.org
Date: Sun, 23 Mar 2014 20:39:43 +0000 (UTC)
From: "Aleksey Yeschenko (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
Message-ID: <JIRA.12685498.1387418927660.128148.1395607183092@arcas>
In-Reply-To: <JIRA.12685498.1387418927660@arcas>
References: <JIRA.12685498.1387418927660@arcas>
Subject: [jira] [Commented] (CASSANDRA-6506) counters++ split counter
 context shards into separate cells
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/CASSANDRA-6506?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13944567#comment-13944567 ] 

Aleksey Yeschenko commented on CASSANDRA-6506:
----------------------------------------------

Any objections to at least committing the first two cleanup commits now (the first one is there to mostly kill all the IDEA warnings, at last, but the second one - c503d6ae89651186b9ac7fc8026eab0ace137af - does deconfuse the API a bit) ?

> counters++ split counter context shards into separate cells
> -----------------------------------------------------------
>
>                 Key: CASSANDRA-6506
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6506
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Aleksey Yeschenko
>            Assignee: Aleksey Yeschenko
>             Fix For: 2.1 beta2
>
>
> This change is related to, but somewhat orthogonal to CASSANDRA-6504.
> Currently all the shard tuples for a given counter cell are packed, in sorted order, in one binary blob. Thus reconciling N counter cells requires allocating a new byte buffer capable of holding the union of the two context's shards N-1 times.
> For writes, in post CASSANDRA-6504 world, it also means reading more data than we have to (the complete context, when all we need is the local node's global shard).
> Splitting the context into separate cells, one cell per shard, will help to improve this. We did a similar thing with super columns for CASSANDRA-3237. Incidentally, doing this split is now possible thanks to CASSANDRA-3237.
> Doing this would also simplify counter reconciliation logic. Getting rid of old contexts altogether can be done trivially with upgradesstables.
> In fact, we should be able to put the logical clock into the cell's timestamp, and use regular Cell-s and regular Cell reconcile() logic for the shards, especially once we get rid of the local/remote shards some time in the future (until then we still have to differentiate between global/remote/local shards and their priority rules).


--
This message was sent by Atlassian JIRA
(v6.2#6252)