Re: native i/o and RCAC - performance

thanks for that input Vern... it has to be something of that nature.
maybe some kind of built in deterministic behavior

Jay

On Thu, May 13, 2021 at 9:06 AM Vern Hamberg <vhamberg@xxxxxxxxxxxxxxx>
wrote:

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

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