Overview

PDU provides powerful data recovery capabilities for various PostgreSQL disaster scenarios. Choose the appropriate recovery method based on your situation.

Choose Your Recovery Scenario

Corrupted Instance

Recover data when the PostgreSQL instance cannot start but PGDATA is still accessible.

Corrupted Data File

Extract data from a single corrupted table data file when PostgreSQL reports file corruption errors.

Single Database Directory

Recover data when an entire database directory is corrupted and the PostgreSQL instance cannot start.

Deleted Records

Recover accidentally deleted records from archived WAL or a preserved copy of PGDATA/pg_wal.

Updated Records

Recover pre-update values from archived WAL or a preserved copy of PGDATA/pg_wal.

Dropped Tables

The only publicly documented practical method to recover DROP TABLE or TRUNCATE without backups using disk fragment scanning.

Unique Capability

Recovery Scenario Comparison

Scenario	Required Configuration	Data Source	Recovery Speed
Corrupted Data File	`PGDATA`	Data file directly	Fast
Corrupted Instance	`PGDATA`	Data file directly	Slower
Single Database Directory	Database directory path	Database directory	Medium
Deleted Records	`PGDATA` + `ARCHIVE_DEST`	WAL archive or checked pg_wal copy	Fast
Updated Records	`PGDATA` + `ARCHIVE_DEST`	WAL archive or checked pg_wal copy	Fast
Dropped Tables	`PGDATA` + `DISK_PATH` + `PGDATA_EXCLUDE`	Disk fragment scanning	Slower

Quick Start

All recovery operations share a common initialization process. Here's the basic workflow:

1. Configure pdu.ini

vim pdu.ini
#PostgreSQL data directory
PGDATA=/home/pg/data
#WAL source: archive directory or checked copy of PGDATA/pg_wal
ARCHIVE_DEST=/data/pdu-backup/incident/pg_wal
#Disk path (required for DROP TABLE recovery)
DISK_PATH=/dev/mapper/data-lv
#All PostgreSQL data directories on DISK_PATH (required for ds idx)
PGDATA_EXCLUDE=/home/pg/data,/home/pg12/data

If ARCHIVE_DEST points to a copied pg_wal directory, run ckwal; after b; and before any scan or restore command.

2. Start PDU and Initialize

./pdu
 
PDU.public=# b;
 
Initializing...
 -pg_database:</home/pg/data/global/1262>
 
Database:postgres
      -pg_schema:</home/pg/data/base/5/2615>
      -pg_class:</home/pg/data/base/5/1259> Total 82 rows
      Schemas:
        ▌ public 10 tables

3. Choose Recovery Method

After initialization, select the appropriate recovery guide from the sidebar based on your scenario.