Re: _cost_equality_semi_join, Peoplesoft, performance issues

  • From: Wolfgang Breitling <breitliw@xxxxxxxxxxxxx>
  • To: jclarke@xxxxxxxxxxxxxxx
  • Date: Wed, 12 Jan 2005 12:32:32 -0700

I have updated a few Peoplesoft systems and I have never changed this 
particular init.ora parameter. Two that I know of (with the potential 
of) causing performance problems in Peoplesoft on 9i are


They changed from false to true from 8i to 9i and I know many Peoplesoft 
installations running on 9i set these back to false.
John Clarke wrote:

> I've recently taken on the role of a DBA for a Peoplesoft upgrade projec=
> t and have a question about =5Fcost=5Fequality=5Fsemi=5Fjoin.
> We're running Oracle on HP-UX 11.00, upgrading from Peoplesoft 7=
> .5 to 8.<something>. During this little project, we'll be upgrading from=
>  7.3.4 to 9iR2, upgrading HP-UX from 11.00 to 11i, and upgrading Peoples=
> oft and its tools, but due to where we're starting and what sort of hard=
> ware we're on, we need to upgrade from 7.3.4 to first, then upgr=
> ade Peoplesoft, then upgrade HP-UX to 11i, then patch Oracle up to 9.2.0=
> .5 or 6.
> Anyway ...
> Since we'll be running Peoplesoft 7.x against for a month or so,=
>  we're in the middle of doing performance/load testing with the version =
> combination. We've found a handful of performance issues that are relate=
> d to us setting =5Fcost=5Fequality=5Fsemi=5Fjoin to FALSE, the non-defau=
> lt value.
> We did this b/c we've found documentation recommending doing this, plus =
> a handful of postings in various places have done this against
> My understanding is that =5Fcost=5Fequality=5Fsemi=5Fjoin needed to be s=
> et to FALSE to circumvent a bug that happens during the Peoplesoft upgra=
> de process, but I'm not sure since my sources are varied and unreliable.
> Does anyone have experience with this parameter against, specifi=
> cally in the context of Peoplesoft=3F If so, I'd be curious to see what =
> sorts of behavior you've seen.
> Thanks,
> John
> --
> //


Wolfgang Breitling
Centrex Consulting Corporation

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