Re: native i/o and RCAC - performance

[Vern Hamberg <vhamberg@xxxxxxxxxxxxxxx>]

Hi Jay

One theory - RCAC is a filter and might result in less I/O, depending on 
the access plan - it is, I believe, using WHERE-clause kind of 
filtering, if I heard things right a while ago. Of course, some of the 
table might be resident in memory after the first loop, a fair test 
normally needs to clear that - there's a command, something about 
access, that I don't have on the tip of my brain right now.

Interesting finding, though!

Vern

On 5/13/2021 7:55 AM, Jay Vaughn wrote:
> Can anyone explain or even theorize when applying RCAC to a file, how it
> boosts the read performance of the file under native i/o?
>
> Example:
>
> file containing 5M rows...
> simple RPG pgm in for loop with reads...
>
> without RCAC applied
> elapsed time - 23s
> processing time - 1.544
>
> with RCAC applied (alter table theTable activate column access control)
> elapsed time - 4s
> processing time - 1.413
>
> drastic change in elapsed time - small change in processing time.
>
> There is also a smaller gain when using SQL but not as much as native i/o.
>
> tia
>
> Jay