OS & Oracle

For the following statement, 9i, 10g  and 11g output the different cardinality and cost.

create table t1
nologging
as
select
trunc(dbms_random.value(0,25)) n1,
rpad(’x',40) ind_pad,
trunc(dbms_random.value(0,20)) n2,
lpad(rownum,10,’0′) small_vc,
rpad(’x',200) padding
from
all_objects
where
rownum <= 10000
;
update t1 set n1 = [...]

Two important and related concepts inside CBO is selectivity and cardinality. The cardinality means that how many rows should be returned by CBO after evaluating the predicates. And this values is always equal to (number of input rows)* selectivity. So we can guess that selectivity means that how many percents of the input rows will [...]