[Question] What compression is used for chunking for a particular chunk store

[elfgoh]

I have a chunk store that was created without --compression, which I understand means it uses the default, zstd. I would like to convert the chunk store to use xz compression in order to save space.

• Is the only way to convert the chunk store compression, from zstd to xz, recreating the chunk store?
• If I had no prior knowledge of the chunk store's compression algorithm, is there any way to determine it?