Re: Null values in indexes

Tom Lane wrote:
> Hannu Krosing <hannu@tm.ee> writes:
> > How hard would it be to _not_ include nulls in indexes
> > as they are not used anyway.
>
> Seems to me that would be a step backwards.
   It  would cause multi-key indexes beeing unusable for partial   key lookup. Imagine you have a key over (a, b, c)
and query   with  WHERE  a = 1 AND b = 2. This query cannot use the index   if a NULL value in c  would  cause  the
index entry  to  be   suppressed.
 


Jan

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