3.2. Mounting a Backup Directory with FUSE #
pg_probackup3 allows running a database instance directly from a backup, inspecting and restoring specific data without requiring a full restore, using the fuse command.
This command implements the FUSE (Filesystem in User Space) mechanism, mounting a virtual representation of the backup directory. Postgres Pro interacts with this mounted directory as if it were an actual PGDATA directory, while proxying all file system requests to the backup files. Since changes are written to the cache rather than the backup, the original backup remains unchanged, and all operations are read-only.
Figure 3.1. The pg_probackup3 FUSE Mechanism
The key use cases for the fuse command are as follows:
Restore deleted data from a particular date (for example, using pg_dump).
Investigate data from a certain point in time.
Provide a read-only production-like environment when a full restore would be time-consuming.
Roll back to a specific moment in time to test and debug application failures.
Run reports on a backup without the overhead of a full restore, as an alternative to replication.
Support developer databases on FUSE without the need to perform a full multi-gigabyte restore.
Note
On ALT Linux, the user running pg_probackup3 must be a member of the fuse group. See the ALT Linux documentation for details.
To use the mounted backup as PGDATA, set mnt_path as the path for the -D parameter when starting Postgres Pro with pg_ctl start.
To ensure sufficient disk space for FUSE operations, use the --cache-dir option to specify a custom directory for cache storage.
Mounting a backup chain requires pre-generated file maps. To enable file map generation, use one of the following methods:
For details on the fuse command and its parameters, refer to the section called “Commands”.