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https://issues.apache.org/jira/browse/HBASE-21856?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16948976#comment-16948976
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Lars Hofhansl commented on HBASE-21856:
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[~bharathv] See description (I mention "Serial Replication" there) :) ... The
thought is that serial replication (i.e. a global ordering) is very expensive
and not always needed.
I propose that for most use cases the ordering I propose here is sufficient. In
the end we should have a discussion about what the specific problem is that we
want to solve.
> Consider Causal Replication Ordering
> ------------------------------------
>
> Key: HBASE-21856
> URL: https://issues.apache.org/jira/browse/HBASE-21856
> Project: HBase
> Issue Type: Brainstorming
> Components: Replication
> Reporter: Lars Hofhansl
> Priority: Major
> Labels: Replication
>
> We've had various efforts to improve the ordering guarantees for HBase
> replication, most notably Serial Replication.
> I think in many cases guaranteeing a Total Replication Order is not required,
> but a simpler Causal Replication Order is sufficient.
> Specifically we would guarantee causal ordering for a single Rowkey. Any
> changes to a Row - Puts, Deletes, etc - would be replicated in the exact
> order in which they occurred in the source system.
> Unlike total ordering this can be accomplished with only local region server
> control.
> I don't have a full design in mind, let's discuss here. It should be
> sufficient to to the following:
> # RegionServers only adopt the replication queues from other RegionServers
> for regions they (now) own. This requires log splitting for replication.
> # RegionServers ship all edits for queues adopted from other servers before
> any of their "own" edits are shipped.
> It's probably a bit more involved, but should be much cheaper that the total
> ordering provided by serial replication.
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