Support for backup via xz

[rouba002]

Hi

I would like to see even basic support for some other archivers, namely XZ (https://tukaani.org/xz/) in WAL and maybe for the backups as well. For large amount of WALs having extra space saved would be a nice benefit.

[mikewallace1979]

Hi @rouba002 - agreed it would be a nice enhancement if Barman had native support for xz compression.

You can achieve the same result with a custom compressor by setting compression = custom and then setting custom_compression_filter, custom_decompression_filter and custom_compression_magic to appropriate values, for example:

compression = custom
custom_compression_filter = xz
custom_decompression_filter = xz -d
custom_compression_magic = 0xFD377A585A00

For backups, we would need pg_basebackup/PostgreSQL to support xz - currently gzip compression can be used with all versions of PostgreSQL, and depending on the version and how it was built, lz4 and zstd compression may also be available. Any available compression can be used by Barman however xz is not supported by any current PostgreSQL versions.