Re: Advised Indexes since 7.3 upgrade

[Charles Wilt <charles.wilt@xxxxxxxxx>]

"account numbers (Approx 185K), dates, and other high key cardinality"
"25 million rows"

Not Sure I'd call 185K out of 25M "high cardinality"...

IBM has recent enhancements that allow for EVI only access, that might be
why your seeing more request.



Charles


On Fri, Aug 31, 2018 at 10:09 AM Jack Prucha <Jack.Prucha@xxxxxxx> wrote:

> There's been a marked change in the number of EVI indexes advised since
> 7.3 was installed.  I cleared the advised indexes for one library before
> the nightly batch run.  Afterwards were the expected Times Advised
> quantities of up to around 60 except for two EVIs which were advised 79K
> times!   Some of the advised EVI indexes have high expensive query
> estimates.
>
> Also the advised indexes are not what are classically (what Dan Cruikshank
> taught us in SQL Tuning and Monitoring Workshop) used for EVIs.  These are
> account numbers (Approx 185K), dates, and other high key cardinality fields.
>
> Has anyone else had similar results since 7.3?
>
> Has the general rule changed for best practices use of EVIs and Radix
> indexes?
>
> One of the files in question is around 25 million rows so I don't want to
> waste a lot time building indexes that aren't that useful.
>
> Thanks in advance.
>
> Jack Prucha
> Programming Team Supervisor
>
> College Foundation, Inc.
> Office Phone: 919.835.2530
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