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Re: [Postgres-xc-developers] Add a new node to the cluster [Feature ID 3608379]
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From: Abbas B. <abb...@en...> - 2013-03-27 12:02:46
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Feature ID 3608379 On Fri, Mar 1, 2013 at 5:48 PM, Amit Khandekar < ami...@en...> wrote: > On 1 March 2013 01:30, Abbas Butt <abb...@en...> wrote: > > > > > > On Thu, Feb 28, 2013 at 12:44 PM, Amit Khandekar > > <ami...@en...> wrote: > >> > >> > >> > >> 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 ? > > > > > > Please take a look at the patch, I am using --restoremode in place of > > --coordinator & --datanode. I am not sure how would stand alone mode fit > in > > here. > > I was trying to see if we can avoid adding a new mode, instead, use > standalone mode for all the purposes for which restoremode is used. > Actually I checked the documentation, it says this mode is used only > for debugging or recovery purposes, so now I myself am a bit hesitent > about this mode for the purpose of restoring. > > > > >> > >> > >>> > >>> 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. > > > > > > Suppose you have a two coordinator cluster. Assume one client connected > to > > each. Suppose one client issues a lock cluster command and the other > issues > > a DDL. Is this what you mean by an ongoing DDL? If true then answer to > your > > question is Yes. > > > > Suppose you have a prepared transaction that has a DDL in it, again if > this > > can be considered an on going DDL, then again answer to your question is > > Yes. > > > > Suppose you have a two coordinator cluster. Assume one client connected > to > > each. One client starts a transaction and issues a DDL, the second client > > issues a lock cluster command, the first commits the transaction. If > this is > > an ongoing DDL, then the answer to your question is No. But its a matter > of > > deciding which camp are we going to put COMMIT in, the allow camp, or the > > deny camp. I decided to put it in allow camp, because I have not yet > written > > any code to detect whether a transaction being committed has a DDL in it > or > > not, and stopping all transactions from committing looks too restrictive > to > > me. > > > > Do you have some other meaning of an ongoing DDL? > > > > I agree that we should have discussed this on the right thread. Lets > > continue this discussion on that thread. > > Continued on the other thread. > > > > >> > >> > >>> > >>> > >>> 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. > > > > > > Yah , but I am giving example of pg_dump so this step has to be there. > > > >> > >> > >> > >>> > >>> 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. > > > > > > Very true. I stand corrected. This means CREATE NODE has to be allowed > when > > xc_lock_for_backup is set. > > > >> > >> > >> > >>> > >>> 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. This message > >>> contains information from EnterpriseDB Corporation that may be > >>> privileged, confidential, or exempt from disclosure under applicable > >>> law. If you are not the intended recipient or authorized to receive > >>> this for the intended recipient, any use, dissemination, distribution, > >>> retention, archiving, or copying of this communication is strictly > >>> prohibited. If you have received this e-mail in error, please notify > >>> the sender immediately by reply e-mail and delete this message. > >>> > >>> > ------------------------------------------------------------------------------ > >>> Everyone hates slow websites. So do we. > >>> Make your web apps faster with AppDynamics > >>> Download AppDynamics Lite for free today: > >>> http://p.sf.net/sfu/appdyn_d2d_feb > >>> _______________________________________________ > >>> Postgres-xc-developers mailing list > >>> Pos...@li... > >>> https://lists.sourceforge.net/lists/listinfo/postgres-xc-developers > >>> > >> > > > > > > > > -- > > -- > > 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. This message > > contains information from EnterpriseDB Corporation that may be > > privileged, confidential, or exempt from disclosure under applicable > > law. If you are not the intended recipient or authorized to receive > > this for the intended recipient, any use, dissemination, distribution, > > retention, archiving, or copying of this communication is strictly > > prohibited. If you have received this e-mail in error, please notify > > the sender immediately by reply e-mail and delete this message. > -- -- 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. This message contains information from EnterpriseDB Corporation that may be privileged, confidential, or exempt from disclosure under applicable law. If you are not the intended recipient or authorized to receive this for the intended recipient, any use, dissemination, distribution, retention, archiving, or copying of this communication is strictly prohibited. If you have received this e-mail in error, please notify the sender immediately by reply e-mail and delete this message. |
