PostgreSQL Streaming Replication

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Streaming Replication:

  1. asynchronous replication
  2. synchronous replication

1.asynchronous replication

Primary Node(192.168.1.201) //install bin and cluster(data) path
Standby Node (192.168.1.202)    // only install bin path

step 1: ssh for both servers

primary node:
su - postgres
ssh-keygen

standby node:
su - postgres
ssh-keygen
primary node:
cd .ssh
ssh-copy-id postgres@192.168.1.202
standby node:
cd .ssh
cat id_rsa.pub >> autheraized_keys
scp autheraized_keys postgres@192.168.1.201:/var/lib/pgsql/.ssh

step 2:primary server configuration:

cd /var/lib/pgsql/11/data

vi pg_hba.conf

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     peer
# IPv4 local connections:
host    all             all             192.168.1.201/32        trust
host    all             all             192.168.1.202/32        trust
host    all             all             127.0.0.1/32            ident
# IPv6 local connections:
host    all             all             ::1/128                 ident
# Allow replication connections from localhost, by a user with the
# replication privilege.
local   replication     all                                     peer
host    replication     all             192.168.1.201/32        trust
host    replication     all             192.168.1.202/32        trust
host    replication     all             127.0.0.1/32            ident
host    replication     all             ::1/128                 ident

vi postgresql.conf
listern_address=*
archive_mode=on
archive_command='cp %p /master_arch/%f && scp %p postgres@192.168.1.202:/slave_arch/%f'
wal_level=replica
full_page_writes=on
max_wal_sender=6
wal_keep_segement=500
max_replication_slot=2
log_statement='all'

Restart the primary server

step 3: take base backup

su - postgres
cd /usr/pgsql-11/bin

without tablespace:
./pg_basebackup -h 192.168.1.201 -p 5432 -P -v -X stream or fetch  -c fast -R -Fp -D /backup/bk_1
with tablespace
./pg_basebackup -h 192.168.1.201 -p 5432 -P -v -c fast -X stream -R -T /tbs_1=/tbs_new1 -T /tbs_2=/tbs_new2mn  -Fp -D /backup/bk_1

cd /backup/bk_1
vi recovery.conf (add commands)
restore_command = 'cp /slave_arch/%f %p'
trigger_file = '/etc/error.txt'
vi postgresql.conf
#archive_command='cp %p /master_arch/%f && scp %p postgres@192.168.1.202:/slave_arch/%f' // disable
hot_standby = on  //enable
start the slave server

step 4: check status

check primary server status:
select * from pg_stat_replication;
check standby server status:
select * from pg_is_in_recovery();
select * from pg_stat_wal_receiver;

2.synchronous replication

same configuration for asynchronous replication but change

step 1:primary server (extra add parameter)
          vi postgresql.conf
              synchronous_standby_names = 'siva'
step 2:standby server
          vi recovery.conf
          primary_conninfo = 'user=postgres host=192.168.1.201 port=5432 application_name=siva'
start the server

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