In production environments, database high availability is the cornerstone of system stability. PostgreSQL provides native streaming replication capabilities that, combined with tools like Patroni and pgpool-II, enable building enterprise-grade high-availability database clusters.
Streaming Replication Configuration
PostgreSQL’s streaming replication achieves primary-standby synchronization through real-time WAL log transfer. Here are the basic configuration steps:
-- Create a replication user on the primary
CREATE ROLE replicator WITH LOGIN REPLICATION PASSWORD 'secure_password';
-- Primary postgresql.conf settings
-- wal_level = replica
-- max_wal_senders = 5
-- wal_keep_size = 1024 -- MB
-- Initialize standby via pg_basebackup
-- pg_basebackup -h primary_host -D /var/lib/postgresql/data \\
-- -U replicator -P -v -R
-- Standby postgresql.conf settings
-- primary_conninfo = 'host=primary_host port=5432 user=replicator password=secure_password'
-- hot_standby = on
-- Check replication status
SELECT client_addr, state, sync_state, write_lag
FROM pg_stat_replication;Patroni HA Management
Patroni uses distributed consensus stores (etcd or Consul) to manage PostgreSQL clusters. When the primary fails, Patroni automatically performs leader election, completing failover within 30 seconds to ensure continuous service. It also provides a REST API for cluster management and monitoring.
Connection Pooling and Backup
pgpool-II offers connection pooling, read-write splitting, and load balancing — distributing read queries to read replicas and routing writes to the primary. pgBackRest supports incremental backups and parallel restore, achieving near-zero RPO backup strategies. Combined, these tools enable PostgreSQL clusters to achieve 99.99% or higher availability.