SBN MPC Wiki
Revision as of 20:44, 4 June 2020 by Mamoutkine (talk | contribs) (Unfold few "default" commands from the users feedback.)
Contents
Postgres database replication.
“Master” side:
- Make sure port 5432 is open.
- As postgres user check postgresql.conf:
listen_addresses should be listening to the replica address. wal_level = logical
- In psql setup an account and give it at least read access to the database and tables to be replicated:
CREATE ROLE <username> WITH REPLICATION LOGIN PASSWORD ‘<password>’; GRANT CREATE ON DATABASE <dbname> TO <username>; GRANT SELECT ON ALL TABLES IN SCHEMA public TO <username>;
- As postgres user edit pg_hba.conf:
In the hosts section add a line like: host <dbname> <username> <user_IP>/32 md5
- Restart the postgres server.
- In psql in the <dbname> create a publication:
[sudo -u postgres] psql <dbname> CREATE PUBLICATION <pubname> FOR ALL TABLES;
- Dump the schema of all tables in the publication and send them to the replica machine:
pg_dump -d <dbname> -t <table1> -s > <table1>_schema.sql pg_dump -d <dbname> -t <table2> -s > <table2>_schema.sql pg_dump -d <dbname> -t <table3> -s > <table3>_schema.sql (can be done for all tables at once by removing the -t option, but above method makes it easier to troubleshoot any issues).
Items 1,2,6 need to be done 1 time.
Items 3,4,5 need to be done with every new replication
Item 7 could be done once, but with every new replication the <username> should be updated in every *_schema.sql file:
GRANT SELECT ON TABLE public.neocp_events TO <username>;
“Replica” side (from the scratch):
- Create an empty database and add empty tables using schemas from “master”:
[sudo -u postgres] psql -d <dbname> -a < <table1>_schema.sql [sudo -u postgres] psql -d <dbname> -a < <table1>_schema.sql [sudo -u postgres] psql -d <dbname> -a < <table1>_schema.sql
- Create a subscription to the master’s publication:
sudo -u postgres psql CREATE SUBSCRIPTION <subname> CONNECTION “host=<master_IP_address> port=5432 user=<username> password=<password> dbname=<dbname>” PUBLICATION <pubname>;
<pubname> in “replica” and “master” sides must match, but the <subname> must not already exist. Multiple subscribers can all connect to the same publication <pubname>.
“Replica” side (with existing logical replication from SBN) - how to add new table(s):
- Download all structure_only.sql file into local disk with reading permission to all
- Add empty tables using schemas from “master”:
[sudo -u postgres] psql -d <dbname> -a < <table1>_schema.sql
- Modify a subscription to the master’s publication:
sudo -u postgres psql <dbname> ALTER SUBSCRIPTION <subscription_name> REFRESH PUBLICATON;