drop table T1 purge;

create table T1 tablespace USERS as
select 
    rownum id,
    case when rownum<10 then mod(rownum,4) else 999 end col1
from   ( select 1 just_a_column
         from DUAL
         connect by level <= 20
       )
/



drop table T2 purge;

create table T2 tablespace USERS as
select 
    rownum id,
    case when rownum<25 then mod(rownum,10) else 999 end col1
from   ( select 1 just_a_column
         from DUAL
         connect by level <= 100
       )
/

exec dbms_stats.gather_table_stats(user,'T1', method_opt=>'for all columns size 1');
exec dbms_stats.gather_table_stats(user,'T2', method_opt=>'for all columns size 1');

alter system flush shared_pool;

drop table Q purge;
create table Q as
select /*+ GATHER_PLAN_STATISTICS */
    T1.ID    id1
  , T2.ID    id2
  , T1.COL1  val
from
    T1,
    T2
where
    T1.COL1=150
  and T1.COL1=T2.COL1
/


select * from table(dbms_xplan.display_cursor(null,null,'ALLSTATS LAST  +PEEKED_BINDS +PARALLEL +PARTITION +COST +BYTES'));


exec dbms_stats.gather_table_stats(user,'T1', method_opt=>'for all columns size 1');
exec dbms_stats.gather_table_stats(user,'T2', method_opt=>'for all columns size 1');

exec dbms_stats.delete_table_stats('SYS','T1');
exec dbms_stats.delete_table_stats('SYS','T2');

exec dbms_stats.gather_table_stats(user,'T1', method_opt=>'for all columns size SKEWONLY');
exec dbms_stats.gather_table_stats(user,'T2', method_opt=>'for all columns size SKEWONLY');


alter system flush shared_pool;


select /*+ GATHER_PLAN_STATISTICS */
    T1.ID
  , T2.ID
  , T1.COL1
from
    T1,
    T2
where
    T1.COL1=3
  and T1.COL1=T2.COL1
/


select * from table(dbms_xplan.display_cursor(null,null,'ALLSTATS LAST  +PEEKED_BINDS +PARALLEL +PARTITION +COST +BYTES'));


@stats_col SYS T1 % % % %
@stats_col SYS T2 % % % %


@hist_cross_freq SYS T1 COL1 SYS T2 COL2