Demai Ni created HBASE-8663:
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Summary: a HBase Shell command to list the tables replicated (from
or to) current cluster
Key: HBASE-8663
URL: https://issues.apache.org/jira/browse/HBASE-8663
Project: HBase
Issue Type: Improvement
Components: Replication
Environment: clusters setup as Master and Slave for replication of
tables
Reporter: Demai Ni
Priority: Minor
This jira is to provide a hbase shell command which can give user can overview
of the tables/columnfamilies currently being replicated. The information will
help system administrator for design and planning, and also help application
programmer to know which tables/columns should be watchout(for example, not to
modify a replicated columnfamily on the slave cluster)
Currently there is no easy way to tell which table(s)/columnfamily(ies)
replicated from or to a particular cluster.
On Master Cluster, an indirect method can be used by combining two steps: 1)
$describe 'usertable' and 2) $list_peers to map the REPLICATION_SCOPE to
target(aka slave) cluster
On slave cluster, this is no existing API/methods to list all the tables
replicated to this cluster.
Here is an example, and prototype for Master cluster
{code: title=hbase shell command:list_replicated_tables |borderStyle=solid}
hbase(main):001:0> list_replicated_tables
TABLE COLUMNFAMILY TARGET_CLUSTER
scores course hdtest017.svl.ibm.com:2181:/hbase
t3_dn cf1 hdtest017.svl.ibm.com:2181:/hbase
usertable family hdtest017.svl.ibm.com:2181:/hbase
3 row(s) in 0.3380 seconds
{code}
{code: title=method to return all columnfamilies replicated from this cluster
|borderStyle=solid}
/**
* ReplicationAdmin.listRepllicated
* @return List of the replicated columnfamilies of this cluster for display.
* @throws IOException
*/
public List<String[]> listReplicated() throws IOException {
List<String[]> replicatedColFams = new ArrayList<String[]>();
HTableDescriptor[] tables;
tables= this.connection.listTables();
Map<String, String> peers = listPeers();
for (HTableDescriptor table:tables) {
HColumnDescriptor[] columns = table.getColumnFamilies();
String tableName = table.getNameAsString();
for (HColumnDescriptor column: columns) {
int scope = column.getScope();
if (scope!=0) {
String[] replicatedEntry = new String[3];
replicatedEntry[0] = tableName;
replicatedEntry[1] = column.getNameAsString();
replicatedEntry[2] = peers.get(Integer.toString(scope));
replicatedColFams.add(replicatedEntry);
}
}
}
return replicatedColFams;
}
{code}
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