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From "Sylvain Lebresne (JIRA)" <j...@apache.org>
Subject [jira] Commented: (CASSANDRA-1938) Use UUID as node identifiers in counters instead of IP addresses
Date Mon, 07 Mar 2011 17:23:59 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-1938?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13003451#comment-13003451
] 

Sylvain Lebresne commented on CASSANDRA-1938:
---------------------------------------------

The problem is with the updateDigest part of PreCompactedRow. For this patch, we need it to
use column updateDigest() function because for counterColumns it's not trivial.

For PreCompactedRow, this mean we should deserialize fully at least for counter CF &&
for updateDigest. I felt the best way to do this was to make PreCompactedRow store the deserialized
and resolved resulting CF and have write and updateDigest do their thing, instead of storing
directly the serialized result.

We could add more special casing for counters, but I actually think that having updateDigest
not use the column updateDigest functions is a mistake in the first place. It does kill the
echoRow optimization, but I'm not sure how useful it is in the first place (especially now
that the 'clear tombstone on minor compaction' optimization make the echoRow one trigger even
less often). 

> Use UUID as node identifiers in counters instead of IP addresses 
> -----------------------------------------------------------------
>
>                 Key: CASSANDRA-1938
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1938
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Sylvain Lebresne
>            Assignee: Sylvain Lebresne
>             Fix For: 0.8
>
>         Attachments: 0001-Use-uuid-instead-of-IP-for-counters.patch, 0002-Merge-old-shard-locally.patch,
0003-Thrift-change-to-CfDef.patch, 1938_discussion
>
>   Original Estimate: 56h
>  Remaining Estimate: 56h
>
> The use of IP addresses as node identifiers in the partition of a given
> counter is fragile. Changes of the node's IP addresses can result in data
> loss. This patch proposes to use UUIDs instead.
> NOTE: this breaks the on-disk file format (for counters)

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