in reply to Re: Much slower DBI on RHEL6
in thread Much slower DBI on RHEL6

MySQL seems to return the data just as fast as it always has, it's the fetching done by perl-DBI that seems much slower on RHEL 6 ( perl 5.10 )

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Re^3: Much slower DBI on RHEL6
by Anonymous Monk on Feb 06, 2014 at 10:20 UTC
    Perl 5.10 IIRC was one of the less optimised Perl versions. I think some benchmarks put it 20-50% slower than 5.8. 5.12 and 5.14 improved the speed much. (Sorry, no sources to back this up at this time.)

      That's exactly right. Perl 5.10.0 accidentally disabled a list assignment optimization. Perl 5.10.1 re-enabled that optimization and a lot of functions which perform list assignment from @_ run faster under 5.10.1 than they did with 5.10.0.

        Hm; I was under the impression that the 5.10.1 patchlevel did not restore the performance -- at least all of it -- and assumed the latest patchlevel with each major version in my statement. That is, my statement was '5.10.1 was slow compared to 5.8.9 and 5.12.4 and 5.14.4'

        But please don't mind me -- I may be talking out of my arse.

Re^3: Much slower DBI on RHEL6
by McA (Priest) on Feb 06, 2014 at 11:08 UTC


    this thread is very interesting. How have you measured that mysql is gathering the informations at the same speed? Can you present the mysql version numbers on the different distributions? Have you checked whether the same query plan is used by mysql?

    Best regards

    P.S.: You use the same hardware for RHEL4 and RHEL6 and the same Linux config?