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<!-- doc/src/sgml/add-node.sgml -->
<chapter id="add-node">
<title>Adding a New Node</title>
<indexterm zone="add-node">
<primary>Add a new node</primary>
</indexterm>
<para>
This chapter outlines steps to add a new Coordinator or a Datanode to a running cluster.
Note that an easier way to do this is to make use of the pgxc_ctl utility.
</para>
<para>
</para>
<sect1 id="add-node-coordinator">
<title>Adding a New Coordinator</title>
<indexterm zone="add-node-coordinator">
<primary>Add a new coordinator</primary>
</indexterm>
<para>
The following steps should be performed to add a new coordinator to a running cluster:
</para>
<para>
<orderedlist>
<listitem>
<para>Initialize the new coordinator. The following example initilizes a coordinator named coord_3.</para>
<programlisting>
/usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data_cord3 --nodename coord_3
</programlisting>
</listitem>
<listitem>
<para>
Make necessary changes in postgresql.conf of the new coordinator,
in particular specify new coordinator name and pooler port.
</para>
</listitem>
<listitem>
<para>
Connect to any of the existing coordinators and lock the cluster for backup, do not close this session.
The following example assumes a coordinator is running on port 5432. Make sure the function call returns true.
The detailed description of the function <function>pgxc_lock_for_backup</> can be found
in <xref linkend="functions-pgxc-add-new-node">
</para>
<programlisting>
./psql postgres -p 5432
select pgxc_lock_for_backup();
</programlisting>
</listitem>
<listitem>
<para>
Connect to any of the existing coordinators and take backup of the database.
Please note that only schema (i.e. no data) is to be dumped.
Also note the use of <option>--include-nodes</>, so that the <command>CREATE TABLE</> contains <command>TO NODE</> clause.
Similarly <option>--dump-nodes</> ensures that the dump does contain existing nodes and node groups.
</para>
<programlisting>
./pg_dumpall -p 5432 -s --include-nodes --dump-nodes --file=/some/valid/path/some_file_name.sql
</programlisting>
</listitem>
<listitem>
<para>
Start the new coordinator specifying <option>--restoremode</> while starting.
The following example starts the new coordinator on port 5455
</para>
<programlisting>
./postgres --restoremode -D ../data_cord3 -p 5455
</programlisting>
<para>
You can use <literal>pg_ctl</literal> with <option>-Z restoremode</option> option.
</para>
<programlisting>
./pg_ctl start -Z restoremode -D ../data_coord3 -p 5455
</programlisting>
</listitem>
<listitem>
<para>
Restore the backup (taken in step 4) by connecting to the new coordinator directly.
</para>
<programlisting>
./psql -d postgres -f /some/valid/path/some_file_name.sql -p 5455
</programlisting>
</listitem>
<listitem>
<para>
Quit the new coordinator.
</para>
</listitem>
<listitem>
<para>
Start the new coordinator specifying <option>--coordinator</> while starting.
The following example starts the new coordinator on port 5455
</para>
<programlisting>
./postgres --coordinator -D ../data_cord3 -p 5455
</programlisting>
</listitem>
<listitem>
<para>
Create the new coordinator on rest of the coordinators and reload configuration.
The following example creates coord_3, with host localhost and port 5455.
</para>
<programlisting>
CREATE NODE COORD_3 WITH (HOST = 'localhost', type = 'coordinator', PORT = 5455);
SELECT pgxc_pool_reload();
</programlisting>
</listitem>
<listitem>
<para>
Quit the session of step 3, this will unlock the cluster. The new coordinator is now ready.
</para>
</listitem>
</orderedlist>
</para>
</sect1>
<sect1 id="add-node-datanode">
<title>Adding a New Datanode</title>
<indexterm zone="add-node-datanode">
<primary>Add a new Datanode</primary>
</indexterm>
<para>
Following steps should be performed to add a new datanode to a running cluster:
</para>
<para>
<orderedlist>
<listitem>
<para>
Initialize the new datanode. The following example initializes a new datanode named data_node_3.
</para>
<programlisting>
/usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data3 --nodename data_node_3
</programlisting>
</listitem>
<listitem>
<para>
Make the necessary changes in postgresql.conf of the new datanode, in particular specify new datanode name
</para>
</listitem>
<listitem>
<para>
Connect to any of the existing coordinators and lock the cluster for backup, do not close this session.
The following example assumes a coordinator is running on port 5432. Make sure the function call returns true.
The detailed description of the function <function>pgxc_lock_for_backup</> can be found
in <xref linkend="functions-pgxc-add-new-node">
</para>
<programlisting>
./psql postgres -p 5432
select pgxc_lock_for_backup();
</programlisting>
</listitem>
<listitem>
<para>
Connect to any of the existing datanodes and take backup of the database.
Please note that only schema (i.e. no data) is to be dumped.
The following example assumes that a datanode is running on port 15432.
</para>
<programlisting>
./pg_dumpall -p 15432 -s --file=/some/valid/path/some_file_name.sql
</programlisting>
</listitem>
<listitem>
<para>
Start the new datanode specifying <option>--restoremode</> while starting the it.
The following example starts the new datanode on port 35432.
</para>
<programlisting>
./postgres --restoremode -D ../data3 -p 35432
</programlisting>
<para>
You can use <literal>pg_ctl</literal> with <option>-Z restoremode</option> option.
</para>
<programlisting>
./pg_ctl start -Z restoremode -D ../data3 -p 5455
</programlisting>
</listitem>
<listitem>
<para>
Restore the backup (taken in step 4) by connecting to the new datanode directly.
</para>
<programlisting>
./psql -d postgres -f /some/valid/path/some_file_name.sql -p 35432
</programlisting>
</listitem>
<listitem>
<para>
Quit the new datanode.
</para>
</listitem>
<listitem>
<para>
Start the new datanode specifying --datanode while starting.
</para>
<programlisting>
./postgres --datanode -D ../data3 -p 35432
</programlisting>
</listitem>
<listitem>
<para>
Create the new datanode on all the coordinators and reload configuration.
The following example creates data_node_3, with host localhost and port 35432.
</para>
<programlisting>
CREATE NODE DATA_NODE_3 WITH (HOST = 'localhost', type = 'datanode', PORT = 35432);
SELECT pgxc_pool_reload();
</programlisting>
</listitem>
<listitem>
<para>
Create the new datanode on all the other datanodes too and reload configuration.
The following example creates data_node_3, with host localhost and port 35432.
</para>
<programlisting>
EXECUTE DIRECT ON (DATA_NODE_1) 'CREATE NODE DATA_NODE_3 WITH (HOST = ''localhost'', type = ''datanode'', PORT = 35432)';
EXECUTE DIRECT ON (DATA_NODE_2) 'CREATE NODE DATA_NODE_3 WITH (HOST = ''localhost'', type = ''datanode'', PORT = 35432)';
EXECUTE DIRECT ON (DATA_NODE_3) 'ALTER NODE DATA_NODE_3 WITH (HOST = ''localhost'', type = ''datanode'', PORT = 35432)';
EXECUTE DIRECT ON (DATA_NODE_1) 'SELECT pgxc_pool_reload()';
EXECUTE DIRECT ON (DATA_NODE_2) 'SELECT pgxc_pool_reload()';
EXECUTE DIRECT ON (DATA_NODE_3) 'SELECT pgxc_pool_reload()';
</programlisting>
</listitem>
<listitem>
<para>
Quit the session of step 3, this will unlock the cluster.
</para>
</listitem>
<listitem>
<para> The new datanode is now ready.
Redistribute existing data by using <command>ALTER TABLE
<replaceable>my_table</replaceable> ADD NODE (DATA_NODE_3)</>.
</para>
</listitem>
</orderedlist>
</para>
</sect1>
</chapter>
|
