On Sun, Dec 30, 2018 at 3:49 AM John Naylor <jcnay...@gmail.com> wrote: > > On 12/29/18, Mithun Cy <mithun...@enterprisedb.com> wrote: > > Results are execution time(unit ms) taken by copy statement when number of > > records equal to exact number which fit HEAP_FSM_CREATION_THRESHOLD = 4 > > pages. For fill factor 20 it is till tid (3, 43) and for scale factor 70 > > till tid (3, 157). Result is taken as a median of 10 runs. > > > So 2-3% consistent regression, And on every run I can see for patch v11 > > execution time is slightly more than base. >
Have you by any chance checked at scale factor 80 or 100? > Thanks for testing! > > > I also tried to insert more > > records till 8 pages and same regression is observed! So I guess even > > HEAP_FSM_CREATION_THRESHOLD = 4 is not perfect! > > That's curious, because once the table exceeds the threshold, it would > be allowed to update the FSM, and in the process write 3 pages that it > didn't have to in the 4 page test. The master branch has the FSM > already, so I would expect the 8 page case to regress more. > It is not clear to me why you think there should be regression at 8 pages when HEAP_FSM_CREATION_THRESHOLD is 4. Basically, once FSM starts getting updated, we should be same as HEAD as it won't take any special path? > What I can do later is provide a supplementary patch to go on top of > mine that only checks the last block. If that improves performance, > I'll alter my patch to only check every other page. > Sure, but I guess first we should try to see what is exactly slowing down via perf report. -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
