On Tue, 1 Sep 2020 at 04:44, Thomas Munro <thomas.mu...@gmail.com> wrote: > > On Tue, Sep 1, 2020 at 7:21 AM Thomas Munro <thomas.mu...@gmail.com> wrote: > > On Sun, Aug 30, 2020 at 11:08 PM Masahiko Sawada > > <masahiko.saw...@2ndquadrant.com> wrote: > > > So my proposal is to add boundary value check in lazy_tid_reaped() > > > before executing bsearch(3). This will help when index vacuum happens > > > multiple times or when garbage tuples are concentrated to a narrow > > > range. > > > > Makes sense if it's often out of range. > > ... though I'm not sure why you need to add extra members to do it?
Indeed. We can use the first and last elements of itemptrs array. > > > > I thought that we can have a generic function wrapping bsearch(3) that > > > does boundary value checks and then does bsearch(3) so that we can use > > > it in other similar places as well. But the attached patch doesn't do > > > that as I'd like to hear opinions on the proposal first. > > > > I wonder if you would also see a speed-up with a bsearch() replacement > > that is inlineable, so it can inline the comparator (instead of > > calling it through a function pointer). I wonder if something more > > like (lblk << 32 | loff) - (rblk << 32 | roff) would go faster than > > the branchy comparator. > > Erm, off course that expression won't work... should be << 16, but > even then it would only work with a bsearch that uses int64_t > comparators, so I take that part back. Yeah, it seems to worth benchmarking the speed-up with an inlining. I'll do some performance tests with/without inlining on top of checking boundary values. Regards, -- Masahiko Sawada http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services