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https://issues.apache.org/jira/browse/HBASE-16415?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16053870#comment-16053870
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Jan Kunigk commented on HBASE-16415:
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Thanks Ted.
I am in the process of implementing the logic of entry redirection in
RedirectingInterClusterReplicationEndpoint, but wonder how I should combine
that class' replicate implementation with redirection.
I would very much appreciate the community once more, while I see several
options:
1. Embed, the logic of redirections into the replicate() method, which would
mean
a) Overriding replicate of HBaseInterClusterReplicationEndpoint, but also
b) duplicating the actual code in
HBaseInterClusterReplicationEndpoint.replicate(), which I don't think is a good
implementation
2. Implement the logic of redirections in a completely new method redirect(),
which needs to be called from within instances of
HBaseInterClusterReplicationEndpoint or
RedirectingInterClusterReplicationEndpoint
We could wrap the content of replicate() into a doReplicate() method in
HBaseInterClusterReplicationEndpoint.
HBaseInterClusterReplicationEndpoint would then only call doReplicate() in
replicate()
RedirectingInterClusterReplicationEndpoint would call redirect(); doReplicate()
as part of replicate()
However, this solution puts the functionality of redirection way down into
HBaseInterClusterReplicationEndpoint, which may not be a good idea.
3. Implement redirect() as an abstract method in HBaseReplicationEndpoint
(which is the abstract base class for HBaseInterClusterReplicationEndpoint and
RegionReplicaReplicationEndpoint.
The redirect() implementation of both HBaseInterClusterReplicationEndpoint and
RegionReplicaReplicationEndpoint would not do anything (optionally logs this).
RedirectingInterClusterReplicationEndpoint.replicate() overrides the empty
implementation with actually redirecting entries.
While this would lead to "empty" abstract method implementations, it appears to
me as the cleanest and most straightforward way to achieve the redirection
logic to occur in the ReplicationEndpoint.
4. Copy the behaviour of getWALEntryfilter() in BaseReplicationEndpoint (This
is more involved, but avoids empty abstract method implementations):
return filters.isEmpty() ? null : new ChainWALEntryFilter(filters);
1. Implement a getRedirector() function in BaseReplicationEnpoint, which
returns an instance of a novel Redirector class, implementing the redirections
logic.
2. If no explicit Redirectors are set in the endpoint, return an empty
redirector (NullRedirector, etc.)
3. Provide a redirectEntries() function in BaseReplicationEndpoint which
will invoke getRedirector() and Redirector.redirect() _if_ getRedirector() !=
null
4. The version in BaseReplicationEnpoint will return an empty redirector
(or null) for getRedirector(), which means that direct subclasses
(HBaseInterClusterReplicationEndpoint or RegionReplicaReplicationEndpoint) will
also return null and not redirect anything
5. The version in RedirectingInterClusterReplicationEndpoint will overwrite
getRedirector() and return a Redirector, which implements
6. Embed redirectEntries() into the replicate() method of
HBaseInterClusterReplicationEndpoint (or all other classes who want to reserve
the option option of redirection)
Again, appreciate your feedback, J
> Replication in different namespace
> ----------------------------------
>
> Key: HBASE-16415
> URL: https://issues.apache.org/jira/browse/HBASE-16415
> Project: HBase
> Issue Type: New Feature
> Components: Replication
> Reporter: Christian Guegi
> Assignee: Jan Kunigk
>
> It would be nice to replicate tables from one namespace to another namespace.
> Example:
> Master cluster, namespace=default, table=bar
> Slave cluster, namespace=dr, table=bar
> Replication happens in class ReplicationSink:
> public void replicateEntries(List<WALEntry> entries, final CellScanner
> cells, ...){
> ...
> TableName table =
> TableName.valueOf(entry.getKey().getTableName().toByteArray());
> ...
> addToHashMultiMap(rowMap, table, clusterIds, m);
> ...
> for (Entry<TableName, Map<List<UUID>, List<Row>>> entry :
> rowMap.entrySet()) {
> batch(entry.getKey(), entry.getValue().values());
> }
> }
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