Overview

Choose a PostgreSQL recovery method based on what remains: data files, WAL, table structures or disk pages.

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

Scan retained disk fragments for data from dropped or truncated tables when no backup is available.

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.

File Identification and Page-Image Recovery

Use Probe when relation files survive with unknown mappings. Use RecoverISO when only a page image and table definitions remain. Follow the corresponding chapter for disk fragments and historical layouts.

Identify Unknown Data Files

Use Probe and ProbeBatch to identify candidate table definitions, then export with confirmed mappings.

Recover Data from a Page Image

Use PDUPlan and RecoverISO to recover data from a PDU page image.

Recover Data from Disk Fragments

Preserve surviving pages and distinguish file identification, image recovery, historical layouts and attribution evidence.