I think the WAL patch (4035cd5d4) should support zstd if library support is
added. A supplementary patch for that already exists.
https://www.postgresql.org/message-id/YNqWd2GSMrnqWIfx@paquier.xyz
There's also some in-progress patches:
- Konstantin and Daniil have a patch to add libpq compression, which ultimately
wants to use zstd.
https://commitfest.postgresql.org/37/3499/
- I had a patch to add zstd to pg_dump, but I ended up storing backups to
ZFS+zstd rather than waiting to progress the patch.
https://commitfest.postgresql.org/32/2888/
Regarding the patch:
I suppose it should support windows, and whatever patches use zstd should
update the install instructions. See 9ca40dcd4, 02a93e7ef, 4035cd5d4.