NAME
pg_combinebackup - reconstruct a full backup from an incremental backup and dependent backups
SYNOPSIS
pg_combinebackup [option...] [backup_directory...]
DESCRIPTION
pg_combinebackup is used to reconstruct a synthetic full backup from an incremental backup and the earlier backups upon which it depends.
Specify all of the required backups on the command line from oldest to newest. That is, the first backup directory should be the path to the full backup, and the last should be the path to the final incremental backup that you wish to restore. The reconstructed backup will be written to the output directory specified by the -o option.
pg_combinebackup will attempt to verify that the backups you specify form a legal backup chain from which a correct full backup can be reconstructed. However, it is not designed to help you keep track of which backups depend on which other backups. If you remove one or more of the previous backups upon which your incremental backup relies, you will not be able to restore it. Moreover, pg_combinebackup only attempts to verify that the backups have the correct relationship to each other, not that each individual backup is intact; for that, use pg_verifybackup(1).
Since the output of pg_combinebackup is a synthetic full backup, it can be used as an input to a future invocation of pg_combinebackup. The synthetic full backup would be specified on the command line in lieu of the chain of backups from which it was reconstructed.
OPTIONS
-d --debug
-n --dry-run
-N --no-sync
-ooutputdir --output=outputdir
-Tolddir=newdir --tablespace-mapping=olddir=newdir
--clone
If a backup manifest is not available or does not contain checksum of the right type, file cloning will be used to copy the file, but the file will be also read block-by-block for the checksum calculation.
File cloning is only supported on some operating systems and file systems. If it is selected but not supported, the pg_combinebackup run will error. At present, it is supported on Linux (kernel 4.5 or later) with Btrfs and XFS (on file systems created with reflink support), and on macOS with APFS.
--copy
--copy-file-range
If a backup manifest is not available or does not contain checksum of the right type, copy_file_range will be used to copy the file, but the file will be also read block-by-block for the checksum calculation.
--manifest-checksums=algorithm
--no-manifest
--sync-method=method
On Linux, syncfs may be used instead to ask the operating system to synchronize the whole file system that contains the backup directory. When the plain format is used, pg_combinebackup will also synchronize the file systems that contain the WAL files and each tablespace. See recovery_init_sync_method for information about the caveats to be aware of when using syncfs.
This option has no effect when --no-sync is used.
-V --version
-? --help
LIMITATIONS
pg_combinebackup does not recompute page checksums when writing the output directory. Therefore, if any of the backups used for reconstruction were taken with checksums disabled, but the final backup was taken with checksums enabled, the resulting directory may contain pages with invalid checksums.
To avoid this problem, taking a new full backup after changing the checksum state of the cluster using pg_checksums(1) is recommended. Otherwise, you can disable and then optionally reenable checksums on the directory produced by pg_combinebackup in order to correct the problem.
ENVIRONMENT
This utility, like most other PostgreSQL utilities, uses the environment variables supported by libpq (see Section 32.15).
The environment variable PG_COLOR specifies whether to use color in diagnostic messages. Possible values are always, auto and never.
SEE ALSO
pg_basebackup(1)