PostgreSQL Data Unloader Complete Manual

PDU recovers PostgreSQL 10–18 data. This documentation is organized by failure type and includes command and parameter references.

Scope

PostgreSQL 10–18

EL 7/8/9 · Ubuntu · Debian

Linux x86 / ARM64

Offline file analysis

Before recovery, copy PGDATA, tablespaces, WAL, and logs. Do not continue writing to the original media.

Common entry points

Recovery scenariosChoose a guide by instance, file, or accidental operation.Usage guideReview configuration, execution order, and outputs.ReferenceFind commands, parameters, supported types, and frequently asked questions.

Recovery scenarios

Confirm the current database state, then select the matching procedure.

File recovery

Database files and directories

The instance is unavailable, or damaged pages must be bypassed for direct file parsing.

Instance cannot startThe instance or system catalogs are damaged and PostgreSQL cannot start.MaterialPGDATAtable structureOutputexported dataCorrupted data fileA relation, data page, or TOAST file is corrupted.Materialrelation filetable structureOutputexported dataSingle database directoryOnly one database directory remains and relation files must be identified again.Materialdatabase directoryDDLOutputexported data

WAL recovery

Accidental DELETE and UPDATE

The database remains available and WAL covering the incident time range has been preserved.

Recover deleted recordsParse DELETE records from the relevant WAL time range.MaterialWALOutputreload dataRecover updated recordsRestore the before-image of one or more incorrectly updated columns.MaterialWALOutputrecovery SQL

Media recovery

Dropped and truncated tables

The table was dropped or truncated and no directly restorable backup is available.

DROP / TRUNCATE tableLocate residual data pages that have not been overwritten in a disk image.Materialdisk imageDDLOutputresidual pages

Basic workflow

Every recovery follows the same evidence preservation, diagnosis, and copy-based workflow.

  1. 1

    Preserve recovery materials

    Copy PGDATA, tablespaces, WAL, and logs, and record the PostgreSQL version.

  2. 2

    Identify the failure type

    Separate instance damage, file damage, accidental DML, and dropped tables.

  3. 3

    Recover from a copy

    Choose the matching commands and verify row counts, parse failures, and results.

Reference

Find command syntax, parameter purpose, and version differences.

Command referenceSyntax and output descriptionsParameter referencePurpose and applicable conditionsSupported data typesEdition and PostgreSQL version differencesFAQAnswers to common recovery questions

Supported data types

Numericsmallint, integer, bigint, numeric, real, double precision, money
Text and binarychar, varchar, text, name, bytea
Date and timedate, time, timestamp, timestamptz, interval
Documents and identifiersjson, jsonb, jsonpath, xml, uuid
Network and systeminet, cidr, macaddr, oid, xid, tid
Advanced typesenum, domain, tsvector, range, multirange, pgvector vector
Enterprise additionsarrays, PostGIS geometry / geography / raster