Logical backups with pg_dump

Last reviewed: 2026-04-08 / Plakar v1.1.0

Overview

The Plakar PostgreSQL integration uses pg_dump and pg_dumpall to produce logical backups which are portable, version-independent SQL representations of your databases. Logical backups can be restored to a different PostgreSQL major version and allow selective restore of individual databases, namespaces, or tables.

For a deeper understanding of SQL dumps and PostgreSQL backup strategies, refer to the official PostgreSQL documentation on SQL dumps.

Requirements

A running PostgreSQL server.
A PostgreSQL superuser, or a user with sufficient privileges to run pg_dump and pg_dumpall.
The following client tools available in $PATH: pg_dump, pg_dumpall, pg_restore, psql.

Managed services (RDS, Cloud SQL, etc.)

On managed services where the administrative user is a restricted superuser and cannot read pg_authid, the integration automatically falls back to --no-role-passwords. The dump is otherwise complete, but restored roles will have no password set.

Install the package

$ plakar pkg add postgresql

What gets stored in a snapshot

Single database backup produces two records:

/globals.sql — roles and tablespaces from pg_dumpall --globals-only.
/<dbname>.dump — the database in pg_dump custom format (-Fc).

Full cluster backup produces one record:

/all.sql — all databases, roles, and tablespaces from pg_dumpall.

Both backup types also include a /manifest.json record written before the dump data, containing cluster-level metadata: server version, roles, tablespaces, databases, schemas, and relation details. See Snapshot manifest below.

Back up a single database

$ plakar source add mypg postgres://postgres:secret@db.example.com/myapp
$ plakar at /var/backups backup @mypg

Back up all databases

Omit the database name to back up the entire cluster with pg_dumpall:

$ plakar source add mypg postgres://postgres:secret@db.example.com/
$ plakar at /var/backups backup @mypg

Restore a single database

The target database must already exist:

$ plakar destination add mypgdst postgres://postgres:secret@db.example.com/myapp
$ plakar at /var/backups restore -to @mypgdst <snapshot_id>

To have Plakar create the database automatically, set create_db=true:

$ plakar destination add mypgdst postgres://postgres:secret@db.example.com/myapp \
  create_db=true
$ plakar at /var/backups restore -to @mypgdst <snapshot_id>

Restore all databases

$ plakar destination add mypgdst postgres://postgres:secret@db.example.com/
$ plakar at /var/backups restore -to @mypgdst <snapshot_id>

List snapshots

$ plakar at /var/backups ls

Source options

Parameter	Default	Description
`location`	—	Connection URI: `postgres://[user[:password]@]host[:port][/database]`
`host`	`localhost`	Server hostname. Overrides the URI host.
`port`	`5432`	Server port. Overrides the URI port.
`username`	—	PostgreSQL username. Overrides the URI user.
`password`	—	PostgreSQL password. Overrides the URI password.
`database`	—	Database to back up. If omitted, all databases are backed up via `pg_dumpall`. Overrides the URI path. When set, a globals dump (`/globals.sql`) is also produced automatically.
`compress`	`false`	Enable `pg_dump` compression. Disabled by default so Plakar’s own compression and deduplication are not degraded.
`schema_only`	`false`	Dump only the schema (no data). Mutually exclusive with `data_only`.
`data_only`	`false`	Dump only the data (no schema). Mutually exclusive with `schema_only`.
`pg_bin_dir`	—	Directory containing the PostgreSQL client binaries. When omitted, binaries are resolved via `$PATH`. Useful when multiple PostgreSQL versions are installed.
`ssl_mode`	`prefer`	SSL mode: `disable`, `allow`, `prefer`, `require`, `verify-ca`, or `verify-full`.
`ssl_cert`	—	Path to the client SSL certificate file (PEM).
`ssl_key`	—	Path to the client SSL private key file (PEM).
`ssl_root_cert`	—	Path to the root CA certificate used to verify the server (PEM).

Destination options

Parameter	Default	Description
`location`	—	Connection URI: `postgres://[user[:password]@]host[:port][/database]`
`host`	`localhost`	Server hostname. Overrides the URI host.
`port`	`5432`	Server port. Overrides the URI port.
`username`	—	PostgreSQL username. Overrides the URI user.
`password`	—	PostgreSQL password. Overrides the URI password.
`database`	—	Target database name. If omitted, inferred from the dump filename (e.g. `myapp.dump` → `myapp`).
`create_db`	`false`	When `true`, passes `-C` to `pg_restore` to create the database from the archive metadata. The `-d` parameter then names only the initial connection database (defaults to `postgres`).
`restore_globals`	`false`	When `true`, feeds `/globals.sql` to `psql` before restoring the database dump. Useful when restoring to a server where source roles do not exist. Not needed for `pg_dumpall` restores (`all.sql`).
`no_owner`	`false`	Pass `--no-owner` to `pg_restore`, skipping `ALTER OWNER` statements. Useful when roles from the source server do not exist on the target.
`schema_only`	`false`	Restore only the schema (no data). Mutually exclusive with `data_only`. Not applicable to `pg_dumpall` restores.
`data_only`	`false`	Restore only the data (no schema). Mutually exclusive with `schema_only`. Not applicable to `pg_dumpall` restores.
`exit_on_error`	`false`	Stop on the first restore error. Applies to both `pg_restore` and `psql`.
`pg_bin_dir`	—	Directory containing the PostgreSQL client binaries. When omitted, binaries are resolved via `$PATH`.
`ssl_mode`	`prefer`	SSL mode: `disable`, `allow`, `prefer`, `require`, `verify-ca`, or `verify-full`.
`ssl_cert`	—	Path to the client SSL certificate file (PEM).
`ssl_key`	—	Path to the client SSL private key file (PEM).
`ssl_root_cert`	—	Path to the root CA certificate used to verify the server (PEM).

Snapshot manifest

Every snapshot includes a /manifest.json record written before the dump data. It captures the cluster state at the time of backup.

Field	Description
`cluster_config`	Key server settings: `data_directory`, `timezone`, `max_connections`, `wal_level`, `server_encoding`, `data_checksums`, `block_size`, `wal_block_size`, `shared_preload_libraries`, `lc_collate`, `lc_ctype`, `archive_mode`, `archive_command_set` (boolean only — the command itself is not stored).
`roles`	All PostgreSQL roles with their attributes and role memberships.
`tablespaces`	All tablespaces with name, owner, filesystem location, and storage options.
`databases`	One entry per database: name, owner, encoding, collation, extensions, schemas, and a `relations` array covering tables, views, materialized views, sequences, and partitioned tables.

Row counts in the manifest are estimates from pg_class and pg_stat_user_tables, not exact values. Metadata collection is best-effort: if a query fails, the affected field is omitted and the backup continues.

Considerations

Compression

Do not enable compress=true unless necessary. Plakar deduplicates and compresses data automatically. Pre-compressed dumps produce an incompressible stream that reduces deduplication effectiveness across snapshots.

Kloset store location

The examples above use /var/backups as the Kloset store. Any supported store backend can be used instead. See Create a Kloset store for details.

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