On Tue, May 17, 2022 at 02:54:28PM -0400, Robert Haas wrote: > I don't particularly have anything against adding Zstandard > compression here, but I wonder whether there's any rush. If we decide > not to add this now, we can always change our minds and add it later, > but if we decide to add it now, there's no backing it out. I'd > probably be inclined to wait and see if our public demands it of us.
+1 One consideration is that zstd with negative compression levels is comparable to LZ4, and with positive levels gets better compression. It can serve both purposes (oltp vs DW or storage-limited vs cpu-limited). If zstd is supported, then for sure at least its compression level should be configurable. default_toast_compression should support it. https://commitfest.postgresql.org/35/3102/ Also, zstd is a few years newer than lz4. Which I hope means that the API is a bit better/further advanced - but (as we've seen) may still be evolving. Zstd allows some of its options to be set by environment variable - in particular, the number of threads. We should consider explicitly setting that to zero in the toast context unless we're convinced it's no issue for every backend (not just basebackup). -- Justin
