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Home -> Community -> Mailing Lists -> Oracle-L -> WHERE 1 = 1 (any info on this)
Morning folks,
the developers here are looking at a view with a where clause which specifies :
WHERE 1=1 AND
............... AND
............... etc.
I'd seen this used before as a way of tweaking the RBO into certain behaviours but it was years ago and my recollection is very hazy. The only explanation I've found so far is :
"the 1=1 is in there to avoid doing repetitive index scans for single rowids, when the app "knows" the result set is going to be manipulated rowid's for a large subset of the table. I would guess your DUAL/CBO example had some similar effect."
Is anyone familiar enough with this tweak to explain it ?
Cheers,
Mike
PS Maybe it'll head off some replies if I make it clear that this view hasn't been generated by code so the "1=1" isn't an accidental artifact It was custom written and is definitely supposed to have exactly this structure.
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Author: Hately, Mike (LogicaCMG)
INET: mike.hately_at_nedl.co.uk
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