Re: [Postgres-xc-developers] Add a new node to the cluster

[Koichi S. <koi...@gm...>]

Abbas;

Thanks a lot for the challenging work.   This is very important
feature to make XC applicable to wider area of installation and
application.

This annotation is very helpful for users as well.

Could you consider to write-up materials to be in reference manual and
Wiki page?

Best;
----------
Koichi Suzuki


2013/2/28 Abbas Butt <abb...@en...>:
> Hi All,
>
> Attached please find a patch that provides a new command line argument for
> postgres called --restoremode.
>
> While adding a new node to the cluster we need to restore the schema of
> existing database to the new node.
> If the new node is a datanode and we connect directly to it, it does not
> allow DDL, because it is in read only mode &
> If the new node is a coordinator, it will send DDLs to all the other
> coordinators which we do not want it to do.
>
> To provide ability to restore on the new node a new command line argument is
> provided.
> It is to be provided in place of --coordinator OR --datanode.
> In restore mode both coordinator and datanode are internally treated as a
> datanode.
> For more details see patch comments.
>
> After this patch one can add a new node to the cluster.
>
> Here are the steps to add a new coordinator
>
>
>  1) Initdb new coordinator
>         /usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data_cord3
> --nodename coord_3
>
>  2) Make necessary changes in its postgresql.conf, in particular specify new
> coordinator name and pooler port
>
>  3) Connect to any of the existing coordinators & lock the cluster for
> backup
>         ./psql postgres -p 5432
>         SET xc_lock_for_backup=yes;
>         \q
>
>  4) Connect to any of the existing coordinators and take backup of the
> database
>         ./pg_dump -p 5432 -C -s
> --file=/home/edb/Desktop/NodeAddition/dumps/101_all_objects_coord.sql test
>
>  5) Start the new coordinator specify --restoremode while starting the
> coordinator
>         ./postgres --restoremode -D ../data_cord3 -p 5455
>
>  6) connect to the new coordinator directly
>         ./psql postgres -p 5455
>
>  7) create all the datanodes and the rest of the coordinators on the new
> coordiantor & reload configuration
>         CREATE NODE DATA_NODE_1 WITH (HOST = 'localhost', type = 'datanode',
> PORT = 15432, PRIMARY);
>         CREATE NODE DATA_NODE_2 WITH (HOST = 'localhost', type = 'datanode',
> PORT = 25432);
>
>         CREATE NODE COORD_1 WITH (HOST = 'localhost', type = 'coordinator',
> PORT = 5432);
>         CREATE NODE COORD_2 WITH (HOST = 'localhost', type = 'coordinator',
> PORT = 5433);
>
>         SELECT pgxc_pool_reload();
>
>  8) quit psql
>
>  9) Create the new database on the new coordinator
>         ./createdb test -p 5455
>
> 10) create the roles and table spaces manually, the dump does not contain
> roles or table spaces
>         ./psql test -p 5455
>         CREATE ROLE admin WITH LOGIN CREATEDB CREATEROLE;
>         CREATE TABLESPACE my_space LOCATION
> '/usr/local/pgsql/my_space_location';
>         \q
>
> 11) Restore the backup that was taken from an existing coordinator by
> connecting to the new coordinator directly
>          ./psql -d test -f
> /home/edb/Desktop/NodeAddition/dumps/101_all_objects_coord.sql -p 5455
>
> 11) Quit the new coordinator
>
> 12) Connect to any of the existing coordinators & unlock the cluster
>         ./psql postgres -p 5432
>         SET xc_lock_for_backup=no;
>         \q
>
> 13) Start the new coordinator as a by specifying --coordinator
>         ./postgres --coordinator -D ../data_cord3 -p 5455
>
> 14) Create the new coordinator on rest of the coordinators and reload
> configuration
>         CREATE NODE COORD_3 WITH (HOST = 'localhost', type = 'coordinator',
> PORT = 5455);
>         SELECT pgxc_pool_reload();
>
> 15) The new coordinator is now ready
>         ./psql test -p 5455
>         create table test_new_coord(a int, b int);
>         \q
>         ./psql test -p 5432
>         select * from test_new_coord;
>
>
> Here are the steps to add a new datanode
>
>
>  1) Initdb new datanode
>         /usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data3 --nodename
> data_node_3
>
>  2) Make necessary changes in its postgresql.conf, in particular specify new
> datanode name
>
>  3) Connect to any of the existing coordinators & lock the cluster for
> backup
>         ./psql postgres -p 5432
>         SET xc_lock_for_backup=yes;
>         \q
>
>  4) Connect to any of the existing datanodes and take backup of the database
>         ./pg_dump -p 15432 -C -s
> --file=/home/edb/Desktop/NodeAddition/dumps/102_all_objects_dn1.sql test
>
>  5) Start the new datanode specify --restoremode while starting the it
>         ./postgres --restoremode -D ../data3 -p 35432
>
>  6) Create the new database on the new datanode
>         ./createdb test -p 35432
>
>  7) create the roles and table spaces manually, the dump does not contain
> roles or table spaces
>         ./psql test -p 35432
>         CREATE ROLE admin WITH LOGIN CREATEDB CREATEROLE;
>         CREATE TABLESPACE my_space LOCATION
> '/usr/local/pgsql/my_space_location';
>         \q
>
>  8) Restore the backup that was taken from an existing datanode by
> connecting to the new datanode directly
>          ./psql -d test -f
> /home/edb/Desktop/NodeAddition/dumps/102_all_objects_dn1.sql -p 35432
>
>  9) Quit the new datanode
>
> 10) Connect to any of the existing coordinators & unlock the cluster
>         ./psql postgres -p 5432
>         SET xc_lock_for_backup=no;
>         \q
>
> 11) Start the new datanode as a datanode by specifying --datanode
>         ./postgres --datanode -D ../data3 -p 35432
>
> 12) Create the new datanode on all the coordinators and reload configuration
>         CREATE NODE DATA_NODE_3 WITH (HOST = 'localhost', type = 'datanode',
> PORT = 35432);
>         SELECT pgxc_pool_reload();
>
> 13) Redistribute data by using ALTER TABLE REDISTRIBUTE
>
> 14) The new daatnode is now ready
>         ./psql test
>         create table test_new_dn(a int, b int) distribute by replication;
>         insert into test_new_dn values(1,2);
>         EXECUTE DIRECT ON (data_node_1) 'SELECT * from test_new_dn';
>         EXECUTE DIRECT ON (data_node_2) 'SELECT * from test_new_dn';
>         EXECUTE DIRECT ON (data_node_3) 'SELECT * from test_new_dn';
>
> Please note that the steps assume that the patch sent earlier
> 1_lock_cluster.patch in mail subject [Patch to lock cluster] is applied.
>
> I have also attached test database scripts, that would help in patch review.
>
> Comments are welcome.
>
> --
> Abbas
> Architect
> EnterpriseDB Corporation
> The Enterprise PostgreSQL Company
>
> Phone: 92-334-5100153
>
> Website: www.enterprisedb.com
> EnterpriseDB Blog: http://blogs.enterprisedb.com/
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