Count fun
- From: "Laimutis Nedzinskas" <Laimutis.Nedzinskas@xxxxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 27 Apr 2006 12:08:17 -0000
Regarding function based indexes.
Is this feature documented or am I hitting a bug, see bellow:
Example:
Create table T (n number)
Insert into T values (1)
--This is Function-based index:
create index I on T ('')
begin dbms_stats.gather_table_stats('SCOTT', 'T', cascade=>true); end;
And then:
select count(*) from T
Result: 0 !
P.S.
This is probably what Oracle is trying to communicate to the audience in
its admin quide:
"The query must be guaranteed not to need any NULL values from the
indexed expression, since NULL values are not stored in indexes."
The fun is that at least a few not null index expression values remedies
the situation...
Fyrirvari/Disclaimer
http://www.landsbanki.is/disclaimer
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