|Subject||Re: [firebird-support] Acsending or Descending Index|
|Author||Vander Clock Stephane|
as always ... thanks ann !
On 1/24/2012 10:01 PM, Ann Harrison wrote:
> > Without the consideration of the order by, i there any difference
> > between ascending and descending index for queries like
> > select ... where fieldA > 123;
> > select ... where fieldA = 123;
> > select ... where fieldA < 123;
> No difference. The direction of the index matters for ORDER BY and
> for MIN (ascending index) or MAX (descending index).
> Ignoring the issues of Nulls, a descending index is identical to an
> ascending index except that the keys are inverted. Nulls are
> complicated in both directions.
> Good luck,
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