On Tue, May 7, 2019 at 10:06 AM Tom Lane <tgl@xxxxxxxxxxxxx> wrote: > Given the described test setup, I'd put basically no stock in these > numbers. It's unlikely that this test case's performance is CPU-bound > per se; more likely, I/O and lock contention are dominant factors. > So I'm afraid whatever they're measuring is a more-or-less chance > effect rather than a real system-wide code improvement. Or a compiler bug. Link-time optimizations give the compiler a view of the program as a whole, not just a single TU at a time. This enables it to perform additional aggressive optimization. -- Peter Geoghegan