Was Data Deleted by Mistake?
Accidental Data Deletion Recovery
Scenario Description
A developer or DBA accidentally executes a DELETE statement without a proper WHERE clause in the production environment, or runs a script that removes critical business data. To make matters worse, the transaction has been committed, and the most recent backup doesn't contain the deleted data.
Typical scenarios include:
- Executing DELETE FROM table_name; forgetting to add WHERE clause
- Test scripts accidentally executed in production
- Scheduled tasks misconfigured causing data cleanup
- Application bugs causing batch deletions
Challenges
In PostgreSQL, once a DELETE operation is committed, the data appears to be gone forever through normal database operations. From the application's perspective, the data has permanently disappeared.
Limitations of Traditional Methods
- - Requires complete physical backup
- - Requires proper PITR setup
- - Recovery time can be lengthy
- - May result in data loss
Common Misconceptions
- - "Data cannot be recovered after commit"
- - "Only backup can recover data"
- - "Need to restore entire database with downtime"
PDU Solution
PDU recovers deleted data by scanning WAL (Write-Ahead Log) archive files. PostgreSQL records all changes in WAL before committing them. PDU leverages this mechanism by parsing WAL records to extract the original deleted data, effectively "undoing" the DELETE operation.
Recovery Principle
PDU Core Capabilities
- Scans WAL archives to find DELETE operations and extract the deleted row data
- Supports time range filtering to narrow down the recovery window
- Transaction ID filtering for precise recovery of specific operations
- Exports recovered data in CSV format for easy reimport
- Non-destructive: original WAL files remain untouched during scanning
- Supports PostgreSQL 10-18 with full data type compatibility
Two Recovery Modes
Time Range Mode
Recover all deleted records within a specified time range. Suitable for batch recovery scenarios.
p resmode time; restore del all;Transaction Mode
Precisely recover specific operations by transaction ID. Suitable for targeted recovery.
p resmode tx; restore del <tx_id>;Prerequisites
- WAL archiving must be enabled
The principle of recovering deleted data involves extracting and integrating data from WAL files.
- Ensure WAL files are archived after deletion
Run after deletion:
SELECT pg_switch_wal(); CHECKPOINT;