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Posted to notifications@accumulo.apache.org by "Josh Elser (JIRA)" <ji...@apache.org> on 2015/03/26 22:50:54 UTC
[jira] [Updated] (ACCUMULO-3174) Avoid mutation copy on remote
replica
[ https://issues.apache.org/jira/browse/ACCUMULO-3174?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Josh Elser updated ACCUMULO-3174:
---------------------------------
Assignee: (was: Josh Elser)
> Avoid mutation copy on remote replica
> -------------------------------------
>
> Key: ACCUMULO-3174
> URL: https://issues.apache.org/jira/browse/ACCUMULO-3174
> Project: Accumulo
> Issue Type: Improvement
> Components: replication
> Reporter: Josh Elser
> Fix For: 1.7.0
>
>
> To ensure that all replicas see mutations applied in the same order as the source, we need to preserve the timestamp on the received mutations to replicate (either user-assigned or server-assigned).
> The way that ServerMutation implements the server-assigned timestamp is done so as to not modify the serialized bytes (for efficiencies sake). The problem arises when the ServerMutation is cast back to a "regular" Mutation, the timestamp that the system assigned, which was tracked outside of the serialized bytes, is lost and a new server-assigned timestamp is used.
> The naive way to circumvent this is to copy the ServerMutation into a new Mutation, checking for a system-assigned timestamp and set that on the updates for each Mutation. This has a big downside as the amount of required heap nearly doubled (assuming that the mutations are the majority of memory used).
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