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https://issues.apache.org/jira/browse/HBASE-26233?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Duo Zhang updated HBASE-26233:
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Release Note:
In this issue we re-implement the 'Async WAL Replication' mechanism fo region
replication, to decouple with the general replication framwork.
Now, we extend the MVCC write entry to be able to carry an action once it is
completed, so we can attach the WAL edits to this action and send them out
directly after the write entry is completed, without touch the actual WAL
system. So the special 'region_replica_replication' peer is also useless.
We also introduce a new replicateToReplica method at region server side for
receiving the WAL edits, which has a much simpler logic than the old replay
method.
After this issue, we do not need to treat META table specially in region
replication, as said above, we do not depend on the general replication
framework any more. But to avoid effecting the usage too much, the 'config
hbase.region.replica.replication.catalog.enabled' is kept, you still need to
enable this flag if you want to enable 'Async WAL Replication' support for META
table.
Rolling upgrading with 'Async WAL Replication enabled is supported. During
rolling upgrading, the 'region_replica_replication' will be removed
automatically after master is upgraded. And at region server side, if the new
replicateToReplica method is not available when it tries to replicate to
secondary replicas, it will fallback to use replay method automatically.
Please related sections in our ref guide are:
http://hbase.apache.org/book.html#async.wal.replication
http://hbase.apache.org/book.html#async.wal.replication.meta
http://hbase.apache.org/book.html#_async_wal_replication_for_meta_table_as_of_hbase_3_0_0
> The region replication framework should not be built upon the general
> replication framework
> -------------------------------------------------------------------------------------------
>
> Key: HBASE-26233
> URL: https://issues.apache.org/jira/browse/HBASE-26233
> Project: HBase
> Issue Type: Umbrella
> Components: read replicas
> Reporter: Duo Zhang
> Assignee: Duo Zhang
> Priority: Major
>
> At least, at the source path, where we track the edits, we should not make
> region replication rely on general replication framework.
> The difficulty here for switching to a table based storage is that, the WAL
> system and replication system highly depend on each other. There will be
> cyclic dependency if we want to store replication peer and queue data in a
> hbase table.
> And after HBASE-18070, even meta wal provider will be integrated together
> with replication system, which makes things more difficult.
> But in general, for region replication, it is not a big deal to lose some
> edits, a flush can fix everything, which means we do not so heavy tracking
> system in the general replication system.
> We should find a more light-weighted way to do region replication.
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