Use OpenZL, Facebook's successor to zstd, for compression

[nickchomey]

Facebook recently open-sourced a new compression framework called OpenZL, which is a successor to zstd. It looks exceptionally impressive, though it requires the data to have a known structure/format - I don't know if that applies at all to rustic. Though, it falls back to zstd if openzl is not useful.

Is it something that rustic might be able to use?

https://engineering.fb.com/2025/10/06/developer-tools/openzl-open-source-format-aware-compression-framework/

[aawsome]

Hi @nickchomey, thanks for pointing to this!

Do you have any special goal in mind about using OpenZL, e.g. using it to compress the metadata stored in the repository?
This is problematic due to the restic-format compatibility we want to keep.

About other data: Given that OpenZL needs and uses information about the structure of the data-to-compress, this makes it hard to impossible to use as a general-purpose-compressor for the blobs/chunks we use in rustic. It could be something if we decide to use something like a pre-processing (pre-compressing) of certain files given specific rules. In this case, however, the solution would most likely work with external commands instead of integrating something like OpenZL directly into rustic..

[nickchomey]

I was only interested in it for the faster and higher compression ratios. But if it can't be useful here, that's fine! Just figured I'd share it just in case. Thanks for checking it out and responding!