dbmsでstatsのバックアップテーブル、バックアップ統計

--  
exec dbms_stats.create_stat_table(user,'mystat');

--  
create table t (id number, name varchar2(30));
begin
  for i in 1 .. 10 loop
    insert into t (id, name) values(i, 'Steven Jobs');
  end loop;
  commit;
end;
/

--  
alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';

--  
exec dbms_stats.gather_table_stats(user,'T',stattab=>'mystat',statid=>'S001');

--  
select table_name, num_rows, last_analyzed from user_tables where table_name='T';

--  mystat ， 
select statid, type, n1 num_rows, d1 last_analyzed
from mystat
where statid='S001' and type='T';

--  5 ， 
insert into t select * from t where rownum<=5;
commit;
exec dbms_stats.gather_table_stats(user,'T',stattab=>'mystat',statid=>'S002');

--  
select table_name, num_rows, last_analyzed from user_tables where table_name='T';

--  mystat ， 10， 
select statid, type, n1 num_rows, d1 last_analyzed
from mystat
where statid='S002' and type='T';