Print lots of debug logging output on stderr.

The -n/--dry-run option instructs pg_combinebackup to figure out what would be done without actually creating the target directory or any output files. It is particularly useful in combination with --debug.

By default, pg_combinebackup will wait for all files to be written safely to disk. This option causes pg_combinebackup to return without waiting, which is faster, but means that a subsequent operating system crash can leave the output backup corrupt. Generally, this option is useful for testing but should not be used when creating a production installation.

Specifies the output directory to which the synthetic full backup should be written. Currently, this argument is required.

Relocates the tablespace in directory olddir to newdir during the backup. olddir is the absolute path of the tablespace as it exists in the final backup specified on the command line, and newdir is the absolute path to use for the tablespace in the reconstructed backup. If either path needs to contain an equal sign (=), precede that with a backslash. This option can be specified multiple times for multiple tablespaces.

Use efficient file cloning (also known as “reflinks” on some systems) instead of copying files to the new data directory, which can result in near-instantaneous copying of the data files.

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.

Perform regular file copy. This is the default. (See also --copy-file-range and --clone.)

Use the copy_file_range system call for efficient copying. On some file systems this gives results similar to --clone, sharing physical disk blocks, while on others it may still copy blocks, but do so via an optimized path. At present, it is supported on Linux and FreeBSD.

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.

Like pg_basebackup, pg_combinebackup writes a backup manifest in the output directory. This option specifies the checksum algorithm that should be applied to each file included in the backup manifest. Currently, the available algorithms are NONE, CRC32C, SHA224, SHA256, SHA384, and SHA512. The default is CRC32C.

Disables generation of a backup manifest. If this option is not specified, a backup manifest for the reconstructed backup will be written to the output directory.

When set to fsync, which is the default, pg_combinebackup will recursively open and synchronize all files in the backup directory. When the plain format is used, the search for files will follow symbolic links for the WAL directory and each configured tablespace.

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.

Prints the pg_combinebackup version and exits.

Shows help about pg_combinebackup command line arguments, and exits.