Re: full-scan vs index for "small" tables

  • From: Nigel Thomas <nigel@xxxxxxxxxxxxxx>
  • To: cary.millsap@xxxxxxxxxx, oracle-l <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 27 Jun 2006 06:33:36 -0700 (PDT)

>The part about "...which can be read in a single I/O call..." is one of those 
>myths that makes sense when you hear it, but it's just >not true. An index 
>scan of a 1-row, 1-block table is more efficient than a full table scan of 
>that table. Try it.

To be fair, the sentence continues (my bold, from 10gR1):
"...a full table scan might be cheaper than an index range scan"

or by implication it might not. Or they could be the same. Or England could win 
the World Cup. Or whatever. Looks like they've got all the angles covered there 
Regards Nigel

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