PostgreSQL Backup and Recovery Best Practices

Introduction

Ensuring data integrity and availability is crucial for any PostgreSQL database. Implementing effective backup and recovery strategies helps safeguard against data loss due to hardware failures, software issues, or human errors. This tutorial provides best practices for backing up and recovering data in PostgreSQL.

Types of Backups

PostgreSQL supports various types of backups, each suitable for different scenarios:

Logical Backups

Logical backups are created using SQL commands and are portable between different PostgreSQL versions. Use the `pg_dump` and `pg_dumpall` utilities to create logical backups.

Example: pg_dump

# Backup a single database
pg_dump -U username -d dbname -F c -b -v -f dbname.backup

Physical Backups

Physical backups involve copying the database files directly. They are faster for large databases but are specific to the PostgreSQL version and platform. Use the `pg_basebackup` utility for physical backups.

Example: pg_basebackup

# Backup the entire database cluster
pg_basebackup -D /path/to/backup -Ft -z -P -U username

Backup Strategies

Develop a backup strategy that meets your business requirements for data loss and recovery time objectives. Common strategies include:

Full Backups

Full backups capture the entire database. Perform full backups regularly, such as weekly or monthly.

Incremental Backups

Incremental backups capture changes since the last full or incremental backup. They are faster and require less storage. Combine incremental backups with full backups to balance performance and storage.

Continuous Archiving and Point-in-Time Recovery (PITR)

Use continuous archiving to capture Write-Ahead Logs (WAL) and enable Point-in-Time Recovery (PITR) for precise recovery.

Example: Continuous Archiving

# postgresql.conf
archive_mode = on
archive_command = 'cp %p /path/to/archive/%f'

Restoring Backups

Restoring from a backup involves loading the backup data into a PostgreSQL instance. The steps vary depending on the backup type.

Restoring Logical Backups

Use the `pg_restore` utility to restore logical backups created with `pg_dump`:

# Restore a database from a logical backup
pg_restore -U username -d dbname -v dbname.backup

Restoring Physical Backups

Restore physical backups by copying the files back to the PostgreSQL data directory and starting the server:

# Stop the PostgreSQL server
pg_ctl stop -D /path/to/data

# Copy the backup files
cp -r /path/to/backup/* /path/to/data/

# Start the PostgreSQL server
pg_ctl start -D /path/to/data

Point-in-Time Recovery (PITR)

To perform a Point-in-Time Recovery, restore the base backup and replay the WAL files up to the desired recovery point:

# postgresql.conf
restore_command = 'cp /path/to/archive/%f %p'
recovery_target_time = 'YYYY-MM-DD HH:MM:SS'

# Start the PostgreSQL server
pg_ctl start -D /path/to/data

Automating Backups

Automate your backup processes using cron jobs or other scheduling tools to ensure regular backups without manual intervention.

Example: Automating with Cron

# Edit the crontab file
crontab -e

# Add a cron job to run pg_dump every day at 2 AM
0 2 * * * pg_dump -U username -d dbname -F c -b -v -f /path/to/backup/dbname.backup

Testing Backups

Regularly test your backups by restoring them to ensure the backup process works correctly and data integrity is maintained.

Example: Testing a Backup

# Create a test database
createdb test_db

# Restore the backup to the test database
pg_restore -U username -d test_db -v /path/to/backup/dbname.backup

Monitoring and Alerts

Set up monitoring and alerts to ensure backups are running as expected and to detect any failures promptly.

Example: Monitoring with pgBackRest

# Install pgBackRest and configure monitoring
apt-get install pgbackrest

# Configure pgBackRest in /etc/pgbackrest/pgbackrest.conf
[global]
repo1-path=/var/lib/pgbackrest
repo1-retention-full=2

[db]
pg1-path=/var/lib/postgresql/10/main