Re: OUTLN

Mark Leith wrote:
>
> Kirti,
>
> I speak to a fair number of DBAs daily, and even bring this up with a fair
> few of them, and have yet to come across a single person that uses this
> package. We have a tool (DBExpert which is a spin-off of SQLExpert from
> Leccotech) that has a "Stored Outline Manager", which is basically a
> graphical front end that aids managing, creating, updating of Stored
> Outlines.
>
> Not one person I have spoken to has lit on to this at all.. I have to say
> that it *does* work as advertised - we've used it to test this new function
> in the tool quite extensively for beta testing.. Whether it's just not
> widely known about (a *lot* of people ask what it actually is), or just not
> worth implementing I'm not sure.. I think there could be quite a good scope
> for them with those apps that *still* run RULE based, and want to be
> migrated quickly and easily to COST / CHOOSE with minimal tuning / re-write
> requirements..
>
> I had no issues with them at all.. The section "Using Plan Stability" in the
> 8i Tuning & Performance manual was very helpful in playing with them, and
> explains in good detail..
>
> HTH
>
> Mark
>

I belong to the immense majority (non-users) but my feeling is that it can be useful for reproducing the behaviour observed on the production database on a smaller volume test database. Now, as when you want to replay something it's rather to rewrite and change the execution plan exporting the stats is probably a far better solution ... I wouldn't like to use it on a production database. For one thing, the plan which looks good today may not be that good tomorrow, because volumes may vary widely. I find a bit pretentious to say 'well, this is the best possible execution plan ever, let's carve it into stone' (this 'end of history' thing). Oracle may well come out in the next release with a very good algorithm for this special case, which the optimizer, which so far has regularly if slowly improved over time, might have used - hadn't you hard-coded the execution plan. I try to avoid hints (not to say that I consider them as a personal failure, but not far ...) and to me a stored outline is a kind of hint raised to the nth power. Don't forget that a successful development will probably outlive 3 or 4 Oracle releases. Collect stats, and give a chance to the guys in Redwood Shores (and those on the East Coast too).

My 2 cents (of euro).

Stephane Faroult
Oriole Ltd

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