115-在oracle数据库表现不佳的SQL,在oceanbase上会怎么样,来看看测试结果-2

select a.object_id,x.id,x.object_id,x.owner
from t1 a
left join 
(select b.*
    , row_number() over (partition by object_id order by id desc) as rn
from t10m b
)x
   on a.object_id=x.object_id and x.rn=1
order by a.created desc
offset 0 rows fetch first 20 rows only
;

select count(*) from 
t1 a
where object_id not in 
(select object_id from t10m 
union all
select object_id from t5m
);

select count(*) 
from t1 a
left join (select object_id,count(*) as cnt from t10m group by object_id)b
 on a.object_id=b.object_id
;

select max(object_id) from t10m where owner='SYS';
注: object_id字段上有索引;

select count(*)
FROM T10m a
WHERE EXISTS
(SELECT 1
 FROM t1 b
 WHERE b.object_name='TAB'
  AND a.object_id = b.object_id
  AND b.created>=a.created  --------非等着关联条件
);