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Re: [Postgres-xc-developers] Add a new node to the cluster
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From: Amit K. <ami...@en...> - 2013-02-28 07:47:35
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On 28 February 2013 10:23, Abbas Butt <abb...@en...> wrote: > 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. > What if we allow writes in standalone mode, so that we would initialize the new node using standalone mode instead of --restoremode ? > 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 > I haven't given a thought on the earlier patch you sent for cluster lock implementation; may be we can discuss this on that thread, but just a quick question: Does the cluster-lock command wait for the ongoing DDL commands to finish ? If not, we have problems. The subsequent pg_dump would not contain objects created by these particular DDLs. > > 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 > > Will pg_dumpall help ? It dumps roles also. > 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 > > Unlocking the cluster has to be done *after* the node is added into the cluster. > 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/ > Follow us on Twitter: http://www.twitter.com/enterprisedb > > This e-mail message (and any attachment) is intended for the use of > the individual or entity to whom it is addressed. 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