On Wed, Mar 13, 2019 at 4:57 PM John Naylor <john.nay...@2ndquadrant.com> wrote: > > On Fri, Mar 8, 2019 at 7:43 PM Amit Kapila <amit.kapil...@gmail.com> wrote: > > > Have you done any performance testing of this patch? I mean to say > > now that we added a new stat call for each table, we should see if > > that has any impact. Ideally, that should be compensated by the fact > > that we are now not transferring *fsm files for small relations. > > To be precise, it will only call stat if pg_class.relpages is below > the threshold. I suppose I could hack a database where all the > relpages values are wrong, but that seems like a waste of time. >
Right. > > How > > about constructing a test where all relations are greater than 4 pages > > and then try to upgrade them. We can check for a cluster with a > > different number of relations say 10K, 20K, 50K, 100K. > > I did both greater and less than 4 pages for 10k relations. Since > pg_upgrade is O(# relations), I don't see a point in going higher. > > First, I had a problem: On MacOS with their "gcc" wrapper around > clang, I got a segfault 11 when compiled with no debugging symbols. > Did you get this problem with the patch or both with and without the patch? If it is only with patch, then we definitely need to investigate. > I > added "CFLAGS=-O0" and it worked fine. Since this doesn't happen in a > debugging build, I'm not sure how to investigate this. IIRC, this > doesn't happen for me on Linux gcc. > > Since it was at least running now, I measured by putting > gettimeofday() calls around transfer_all_new_tablespaces(). I did 10 > runs each and took the average, except for patch/1-page case since it > was obviously faster after a couple runs. > > 5 pages: > master patch > 5.59s 5.64s > > The variation within the builds is up to +/- 0.2s, so there is no > difference, as expected. > > 1 page: > master patch > 5.62s 4.25s > > Clearly, linking is much slower than stat. > The results are fine. Thanks for doing the tests. -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com