Re: WAL compression setting after PostgreSQL LZ4 default change

[Andrey Borodin]

> On 31 Jul 2026, at 18:10, Christoph Berg <m...@debian.org> wrote:
> 
> zstd for WAL

FWIW on 19beta2, one client: a seqscan setting hint bits on a freshly
checkpointed 380MB table with wal_log_hints on, so ~47k full-page images
and little else.  Best of three: off 765ms, pglz 1402ms, lz4 444ms, zstd
797ms, writing 382/105/107/67 MB of WAL (fsync off, so the I/O saving is
understated).  lz4 is the only setting faster than no compression at all,
while pglz costs nearly double for the size lz4 gives away for free.  zstd
compresses a third better but pays for it in CPU, partly by allocating a
ZSTD_CCtx per FPI - see the nearby thread "Compression of bigger WAL
records".  +1 for "on" meaning lz4 where available.


Best regards, Andrey Borodin.