On Mon, May 19, 2025 at 3:37 PM Andres Freund <and...@anarazel.de> wrote: > I think we can do better - something like > > #ifdef PG_HAVE_8BYTE_SINGLE_COPY_ATOMICITY > lsn = PageGetLSN(page); > #else > buf_state = LockBufHdr(bufHdr); > lsn = PageGetLSN(page); > UnlockBufHdr(bufHdr, buf_state); > #endif > > All perf relevant systems support reading 8 bytes without a chance of > tearing...
Even assuming that this scheme works perfectly, I'd still like to pursue the idea I had about fixing this in nbtree. The relevant nbtree code seems more elegant if we avoid calling BufferGetLSNAtomic() unless and until its return value might actually be useful. It's quite a lot easier to understand the true purpose of so->currPos.lsn with this new structure. -- Peter Geoghegan
