Recovering from a Crash or Loss of Data
Explore methods to recover PostgreSQL databases after a crash or data loss. Understand using backup files with pg_dump and pg_restore, implement replication for real-time data copies, and perform point-in-time recovery using WAL files. Learn how to safely reset the Write-Ahead Log to maintain data consistency and prepare for disaster recovery scenarios.
In a perfect world, data would never be lost or corrupted, but unfortunately, this is not the case. Database crashes, hardware failures, and software bugs can all result in data loss. For this reason, it’s crucial to have a strategy to recover our data if disaster strikes.
Using backup files
One of the most straightforward data recovery methods is using backup files. Backups are copies of our data made at regular intervals and stored safely. In the event of a data loss, we can restore our database to a previous state using a backup file.
In PostgreSQL, we can use the pg_dump and pg_restore commands to create and restore backup files, respectively. The pg_dump command is used to create a backup file in the format of our choice, such as plain SQL, tar, or custom format. The pg_restore command is used to restore a backup file to a database.
It’s essential to test our backup files regularly to ensure they can be used for recovery during a disaster. Additionally, storing backup files in multiple locations, such as on-site and off-site, is a good practice to reduce the risk of losing them.
Using replication
Another method of data recovery is to use replication. Replication is copying data from one database to another, typically in real time. In the event of a data loss, we can promote a replica to become the primary database, allowing us to recover our data.