Re: Statistics collection

[Jim Oberholtzer <midrangel@xxxxxxxxxxxxxxxxx>]

John,  

Unless your system is in stress I would doubt you'll notice it

Jim Oberholtzer
Agile Technology Architects
Office:  414-433-4363
Cell:     414-915-1445
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"I've learned that courage is not the absence of fear, but the triumph over it.  The brave man is not he who does not feel afraid,  but he who conquers that fear".   --  Nelson Mandela



> On Nov 7, 2016, at 2:29 PM, Maassel, John R. <John_Maassel@xxxxxxxxxxxx> wrote:
>
> We upgraded from 6.1 to 7.2 over the weekend.
>
> We started getting reports that some ETL jobs weren't finishing in the normal amount of time. I'm attributing this to the new SQE and optimizer and have been helping rewrite queries. While troubleshooting this, we found that there aren't statistics on most of the tables involved, and the ones that have stats are stale. Poking around in system values, I found that QDBFSTCCOL is set to *NONE, which I think means that it isn't automatically refreshing stats when the optimizer thinks it's needed. I think it's been like that for a long time. Since the tables are rather large (~3 billion records in one) I think the lack of statistics is probably a major factor. Is that accurate?
>
> I'm proposing that we set that system value to *ALL. Will that adversely affect the system performance or DASD utilization? Should we do this during a slow time (right after an IPL, for example) or can this be changed on the fly?
>
> Thanks,
>
> --
> John Maassel
> Lead Programmer/Analyst - Food Products & Corporate Systems
>
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