Re: Embedded SQL/Index/Speed/How

There's a system wide SQL plan cache...you can see it by right
clicking on database in iNav....

I suppose it's possible that having the index changed the plan in the
cache even if the index wasn't directly used...

When you say it ran "dog slow", did you run it more than once?

It's possible the system created a temporary index index at some
point, which I don't believe is necessarily deleted automatically when
a matching permanent index is created. Thus: it's possible the
temporary index is still around....

What did VE show you on the "dog slow" runs vs. now?

Honestly, it's pretty much impossible to say what happen based upon
what you've told us.

You might see if you can still find the "dog slow" runs in the plan
cache...there's an analyze function that might tell you more..

Lastly, consider taking SQL plan cache snapshots before you start
messing with stuff...then have something to compare to after you've
seen a change in behavior.

For more info:
http://systeminetwork.com/node/26693
http://systeminetwork.com/article/5-essential-ways-use-iseries-navigator-sql-plan-cache

HTH,
Charles



On Wed, Mar 23, 2011 at 12:32 PM, Michael Ryan <michaelrtr@xxxxxxxxx> wrote:

Ok...a co-worker had a program with an embedded SQL statement,
selecting records with a number of different criteria. It ran dog
slow. I suggested creating an index to remove some of the 'fixed'
criteria. Did that, recreated the program, ran like the wind. Then we
decided to test things out. Deleted the index. Still ran fast. Used an
old copy of the program that was created before the index was made.
Still ran fast. Deleted the index and the program, recreated the
program. Still ran fast.

What happened? Was an access plan created and stored someplace? I
would think deleting the program and index and recreating the program
would remove any consideration of an access path.

Thanks for any thoughts.
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