SLONY Replication and PG POOL II

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1 SLONY Replication and PG POOL II Except where otherwise noted, this work is licensed under

2 Session Topics SLONY Replication PG POOL II

3 SLONY Replication SLONY is a Master to Multiple Slaves Replication System Topics We'll Cover: Installation and General Info Creating and activating a replication set Methods for Failover & Switchover Note: Thie is ONE way to setup SLONY, not necessarily the only way

4 SLONY Installation Download Uncompress Configure./configure [options]./configure with-pgconfigdir=<dir> \ --with-pgbindir=<dir> \ --with-pgsharedir=<dir> Make Make Install (as root)

5 SLONY The SLONIK Preamble Each server to be included in the cluster must be prepared Slony will create a schema on each node (i.e. if your replication cluster is named customer then slony will create a schema on each node called _customer.) Allow slony to create this cluster schema itself (i.e. keep your hands off) The same preamble must be included in each slonik script to manage the cluster : cluster name = customer; node 1 admin conninfo = 'dbname=custdb host=yoda user=slony'; node 2 admin conninfo = 'dbname=custdb host=r2d2 user=slony'; node 3 admin conninfo = 'dbname=custdb host=c3po user=slony';

6 SLONY General Info The database must exist on all nodes The PL/pgSQL language must be installed on all nodes Connection Strings and passwords (use trust or a.pgpass file)

7 SLONY Create Variable File The use of a variables file can help you manage the setup process Example (slony_setup.env): export CLUSTERNAME=sample_rep export MASTERDBNAME=slony_test export MASTERHOST=localhost export MASTERPORT=5444 export SLAVEDBNAME=slony_test export SLAVEHOST=localhost export SLAVEPORT=5445 export REPUSER=postgres

8 SLONY Create / Prepare Slave Node Create the database on the slave node Replicate users on the slave node Create the database structures (DDL) on the slave node Install PL/pgSQL on the slave node

9 SLONY Initialize the replication cluster Initialize the replication cluster Create a replication set Add tables to the replication set Store the slave node Store paths

10 SLONY Start the slon daemons $ slon [options] clustername [connection string] Options: -h print usage message and exit -v print version and exit -d <debuglevel> verbosity of logging (1..4) -s <milliseconds> SYNC check interval (default 10000) -t <milliseconds> SYNC interval timeout (default 60000) -o <milliseconds> desired subscriber SYNC processing time -g <num> maximum SYNC group size (default 6)

11 SLONY Start the slon daemons More Options More Options: -c <num> how often to vacuum in cleanup cycles -p <filename> slon pid file -f <filename> slon configuration file -a <directory> directory to store SYNC archive files (SLONY Log Shipping) -x <command> program to run after writing archive file -q <num> Terminate when this node reaches # of SYNCs -r <num> # of syncs for -q option -l <interval> this node should lag providers by this interval

12 SLONY Start replication Subscribe set SUBSCRIBE SET ( ID = 1, PROVIDER = 1, RECEIVER = 3, FORWARD = YES );

13 SLONY Switchover lock set (id = 1, origin = 1); wait for event (origin = 1, confirmed = 2); move set (id = 1, old origin = 1, new origin = 2); wait for event (origin = 1, confirmed = 2);

14 SLONY Failover failover (id = 1, backup node = 2); drop node (id = 1, event node = 2);

15 SLONY Live Example

16 SLONY Summary

17 PG POOL II

18 PG POOL II Overview Connection Pooling Connections beyond max_connections are queued instead of rejected Replication Load Balancing Parallel Query

19 PG POOL II Installation Prerequisites PostgreSQL header files libpq make

20 PG POOL II Installation Install PostgreSQL on all nodes Install pgpool on node 1./configure --prefix=<install dir> \ e.g.: --with-pgsql=<path to top level pg install dir>./configure --prefix=/usr/local/pgsql/pgpool \ --with-pgsql=/usr/local/pgsql/pg841 $ make $ sudo make install Chown -R postgres:postgres <install dir>

21 PG POOL II Configuration <install dir>/etc/pgpool.conf (copied from pgpool.conf.sample) # connections listen_addresses = 'localhost' # Port number for pgpool port = 9999

22 PG POOL II Configuration (cont) # number of pre-forked child process num_init_children = 32 # Number of connection pools allowed for a child process max_pool = 4 # If idle for this many seconds, child exits. 0 means no timeout. child_life_time = 300 # If idle for this many seconds, connection to PostgreSQL closes. # 0 means no timeout. connection_life_time = 0

23 PG POOL II Configuration (cont) # If child_max_connections connections were received, child exits. # 0 means no exit. child_max_connections = 0 # If client_idle_limit is n (n > 0), the client is forced to be # disconnected whenever after n seconds idle (even inside an explicit # transactions!) # 0 means no disconnect. client_idle_limit = 0

24 PG POOL II Configuration (cont) # Maximum time in seconds to complete client authentication. # 0 means no timeout. authentication_timeout = 60 # Logging directory logdir = '/tmp' # pid file name #pid_file_name = '/var/run/pgpool/pgpool.pid' pid_file_name = '/usr/local/pgsql/pgpool/etc/pgpool.pid'

25 PG POOL II Configuration (cont) # Replication mode replication_mode = false # Load balancing mode, i.e., all SELECTs are load balanced. # This is ignored if replication_mode is false. load_balance_mode = false # if there's a data mismatch between master and secondary # start degeneration to stop replication mode replication_stop_on_mismatch = false

26 PG POOL II Configuration (cont) # If true, replicate SELECT statement when load balancing is disabled. # If false, it is only sent to the master node. replicate_select = false # Semicolon separated list of queries to be issued at the end of a session reset_query_list = 'ABORT; RESET ALL; SET SESSION AUTHORIZATION DEFAULT' # for 8.3 or newer PostgreSQL versions DISCARD ALL can be used as # follows. However beware that DISCARD ALL holds exclusive lock on # pg_listener so it will be a serious performance problem if there are # lots of concurrent sessions. # reset_query_list = 'ABORT; DISCARD ALL'

27 PG POOL II Configuration (cont) # If true print timestamp on each log line. print_timestamp = true # If true, operate in master/slave mode. master_slave_mode = false # If true, cache connection pool. connection_cache = true

28 PG POOL II Configuration (cont) # Health check timeout. 0 means no timeout. health_check_timeout = 20 # Health check period. 0 means no health check. health_check_period = 0 # Health check user health_check_user = 'nobody'

29 PG POOL II Configuration (cont) # Execute command by failover. # special values: %d = node id # %h = host name # %p = port number # %D = database cluster path # %m = new master node id # %M = old master node id # %% = '%' character # failover_command = ''

30 PG POOL II Configuration (cont) # Execute command by failback. # special values: %d = node id # %h = host name # %p = port number # %D = database cluster path # %m = new master node id # %M = old master node id # %% = '%' character # failback_command = ''

31 PG POOL II Configuration (cont) # If true, automatically locks a table with INSERT statements to keep # SERIAL data consistency. If the data does not have SERIAL data # type, no lock will be issued. An /*INSERT LOCK*/ comment has the # same effect. A /NO INSERT LOCK*/ comment disables the effect. insert_lock = true # If true, ignore leading white spaces of each query while pgpool judges # whether the query is a SELECT so that it can be load balanced. This # is useful for certain APIs such as DBI/DBD which is known to adding an # extra leading white space. ignore_leading_white_space = true

32 PG POOL II Configuration (cont) # If true, print all statements to the log. Like the log_statement option # to PostgreSQL, this allows for observing queries without engaging in full # debugging. # log_statement = false log_statement = true # If true, incoming connections will be printed to the log. log_connections = false # If true, hostname will be shown in ps status. Also shown in # connection log if log_connections = true. # Be warned that this feature will add overhead to look up hostname. log_hostname = false

33 PG POOL II Configuration (cont) # if non 0, run in parallel query mode parallel_mode = false # if non 0, use query cache enable_query_cache = false #set pgpool2 hostname pgpool2_hostname = ' '

34 PG POOL II Configuration (cont) # system DB info #system_db_hostname = 'localhost' #system_db_port = 5432 #system_db_dbname = 'pgpool' #system_db_schema = 'pgpool_catalog' #system_db_user = 'pgpool' #system_db_password = ''

35 PG POOL II Configuration (cont) # backend_hostname, backend_port, backend_weight # here are examples backend_hostname0 = ' ' backend_port0 = 5432 backend_weight0 = 1 backend_data_directory0 = '/usr/local/pgsql/pg841/data' #backend_hostname1 = 'host2' #backend_port1 = 5433 #backend_weight1 = 1 #backend_data_directory1 = '/data1'

36 PG POOL II Configuration (cont) # - HBA - # If true, use pool_hba.conf for client authentication. In pgpool-ii # 1.1, the default value is false. The default value will be true in # 1.2. enable_pool_hba = false

37 PG POOL II Configuration (cont) # - online recovery - # NOTE: these values are used to re-attach (after failure) a node or to attach a new node # when pgpool replication is used # online recovery user recovery_user = 'nobody' recovery_password = '' recovery_1st_stage_command = '' recovery_2nd_stage_command = '' # maximum time in seconds to wait for the recovering node's postmaster # start-up. 0 means no wait. recovery_timeout = 90

38 Start PG POOL $ cd <install dir>/bin $./pgpool -n > log 2>&1 &

39 Controlling PG POOL Usage: pgpool [ -c] [ -f CONFIG_FILE ] [ -F PCP_CONFIG_FILE ] [ -a HBA_CONFIG_FILE ] [ -n ] [ -d ] pgpool [ -f CONFIG_FILE ] [ -F PCP_CONFIG_FILE ] [ -a HBA_CONFIG_FILE ] [ -m SHUTDOWN-MODE ] stop pgpool [ -f CONFIG_FILE ] [ -F PCP_CONFIG_FILE ] [ -a HBA_CONFIG_FILE ] reload

40 Controlling PG POOL (cont) Common options: -a HBA_CONFIG_FILE Sets the path to the pool_hba.conf configuration file (default: /usr/local/pgsql/pgpool/etc/pool_hba.conf) -f CONFIG_FILE Sets the path to the pgpool.conf configuration file (default: /usr/local/pgsql/pgpool/etc/pgpool.conf) -F PCP_CONFIG_FILE Sets the path to the pcp.conf configuration file (default: /usr/local/pgsql/pgpool/etc/pcp.conf) -h Prints this help

41 Controlling PG POOL (cont) Start options: -c Clears query cache (enable_query_cache must be on) -n Don't run in daemon mode, does not detach control tty -d Debug mode Stop options: -m SHUTDOWN-MODE Can be "smart", "fast", or "immediate" Shutdown modes are: smart fast quit after all clients have disconnected quit directly, with proper shutdown immediate quit without complete shutdown; will lead to recovery on restart

42 End2End Live Example (If Time Allows)

43 End

Setting up irods High Availability using Pgpool in NorStore

Setting up irods High Availability using Pgpool in NorStore This is a slightly modified version of: https://www.irods.org/index.php/ irods_high_avaliability Note: I call Server1 throughout the document