On Sat, May 22, 2021 at 3:10 AM Tomas Vondra <tomas.von...@enterprisedb.com> wrote: > > On 5/21/21 6:43 PM, Andres Freund wrote: > > Hi, > > > > ... > > > >> Attached are the flame graphs for all three cases. The change in master is > >> pretty clearly visible, but I don't see any clear difference between old > >> and > >> patched code :-( > > > > I'm pretty sure it's the additional WAL records? > > > > Not sure. If I understand what you suggested elsewhere in the thread, it > should be fine to modify heap_insert to pass the page recptr to > visibilitymap_set, roughly per the attached patch. > > I'm not sure it's correct, but it does eliminate the Heap2/VISIBILITY > records for me (when applied on top of your patch). Funnily enough it > does make it a wee bit slower: > > patch #1: 56941.505 > patch #2: 58099.788 > > I wonder if this might be due to -fno-omit-frame-pointer, though, as > without it I get these timings: > > 0c7d3bb99: 25540.417 > master: 31868.236 > patch #1: 26566.199 > patch #2: 26487.943 > > So without the frame pointers there's no slowdown, but there's no clear > improvement after removal of the WAL records either :-(
Can we verify that the additional WAL records are the cause of this difference by making the matview unlogged by manually updating relpersistence = 'u'? Here are the results of benchmarks with unlogged matviews on my environment: 1) head: 22.927 sec 2) head w/ Andres’s patch: 16.629 sec 3) before 39b66a91b commit: 15.377 sec 4) head w/o freezing tuples: 14.551 sec And here are the results of logged matviews ICYMI: 1) head: 42.397 sec 2) head w/ Andres’s patch: 34.857 sec 3) before 39b66a91b commit: 32.556 sec 4) head w/o freezing tuples: 32.752 sec There seems no difference in the tendency. Which means the additional WAL is not the culprit? Interestingly, my previously proposed patch[1] was a better performance. With the patch, we skip all VM-related work on all insertions except for when inserting a tuple into a page for the first time. logged matviews: 31.591 sec unlogged matviews: 15.317 sec Regards, [1] https://www.postgresql.org/message-id/CAD21AoAaiPcgGRyJ7vpg05%3DNWqr6Vhaay_SEXyZBboQcZC8sFA%40mail.gmail.com Regards, -- Masahiko Sawada EDB: https://www.enterprisedb.com/
