AW: Original design approach to Oracle REDO Logs

To play devils advocate, wouldn’t the dynamic addition of the „set“ columns into the „where“ clause play havoc with the execution plan stability? Think adaptive cursor sharing.

Mike

http://www.strychnine.co.uk

> Am 18/06/2021 um 15:15 schrieb Clay Jackson (Redacted sender "Clay.Jackson" for DMARC) <dmarc-noreply_at_freelists.org>:
>
> MWF wrote:
> “At the query level I wonder if permuting the query when it can be certainly iso-functional as
> update someTable
> set someColumn1 = 1.234
> becomes
> update someTable
> set someColumn1 = 1.234
> where someColumn1 != 1.234”
>
> I almost can’t believe I’m suggesting this; but is there a nugget of an “enhancement” request in there? I could see cases where if the optimizer was going to do an index lookup (i.e. there was a unique index on that column), OR, a full table scan (i.e. NO other path) a query rewrite might give some dramatic results (I think any paths other than “direct index” or full table scan would probably not be deterministic enough to “take a chance”).
>
> Clay Jackson

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