结论是存储在 remote 端，这其实也很好理解。在远端能高效率地计算，当然应当在远端完成缓存和检索。
■ Before query execution via DBLINK:
===========
DBLINK destination (remote side):
conn u2 / u2
create table tab002 as select * from dba_objects;
shu immediate
startup
select o.owner, o.object_name, o.object_type, s.buffer_pool, count (*) buffer
from dba_objects o, v $ bh b, dba_segments s
where b.objd = o.data_object_id
and o.owner = 'U 2'
and o.object_name = s.segment_name
and o.object_type = s.segment_type
group by o.owner, o.object_name, o.object_type, o.status, s.buffer_pool
order by buffers;
A record was not selected.
===========
Local side:
conn u3 / u3
select o.owner, o.object_name, o.object_type, s.buffer_pool, count (*) buffer
from dba_objects o, v $ bh b, dba_segments s
where b.objd = o.data_object_id
and o.owner = 'U 2'
and o.object_name = s.segment_name
and o.object_type = s.segment_type
group by o.owner, o.object_name, o.object_type, o.status, s.buffer_pool
order by buffers;
A record was not selected.
select o.owner, o.object_name, o.object_type, s.buffer_pool, count (*) buffer
from dba_objects o, v $ bh b, dba_segments s
where b.objd = o.data_object_id
and o.owner = 'U3'
and o.object_name = s.segment_name
and o.object_type = s.segment_type
group by o.owner, o.object_name, o.object_type, o.status, s.buffer_pool
order by buffers;
A record was not selected.
■ Query execution via DBLINK:
SQL> select count (*) from tab002 @ dbk;
COUNT (*)
----------
69263
conn u3 / u3
select o.owner, o.object_name, o.object_type, s.buffer_pool, count (*) buffer
from dba_objects o, v $ bh b, dba_segments s
where b.objd = o.data_object_id
and o.owner = 'U 2'
and o.object_name = s.segment_name
and o.object_type = s.segment_type
group by o.owner, o.object_name, o.object_type, o.status, s.buffer_pool
order by buffers;
A record was not selected. <<<<<<<<<<< Cache has no related information
select o.owner, o.object_name, o.object_type, s.buffer_pool, count (*) buffer
from dba_objects o, v $ bh b, dba_segments s
where b.objd = o.data_object_id
and o.owner = 'U3'
and o.object_name = s.segment_name
and o.object_type = s.segment_type
group by o.owner, o.object_name, o.object_type, o.status, s.buffer_pool
order by buffers;
A record was not selected. <<<<<<<<<<< Cache has no related information
===========
DBLINK destination (remote side):
select o.owner, o.object_name, o.object_type, s.buffer_pool, count (*) buffer
from dba_objects o, v $ bh b, dba_segments s
where b.objd = o.data_object_id
and o.owner = 'U 2'
and o.object_name = s.segment_name
and o.object_type = s.segment_type
group by o.owner, o.object_name, o.object_type, o.status, s.buffer_pool
order by buffers;
OWNER
-------------------------------------------------------------------- ------------------------------
OBJECT_NAME
-------------------------------------------------------------------- ------------------------------
OBJECT_TYPE BUFFER_POOL
-------------------------------------------------------------------- ------- ---------------------
BUFFERS
----------
U2
TAB 002
TABLE DEFAULT
2042 <<<<<<<<<<<<<<<<<< data got into the cache.
select o.owner, o.object_name, o.object_type, s.buffer_pool, count (*) buffer
from dba_objects o, v $ bh b, dba_segments s
where b.objd = o.data_object_id
and o.owner = 'U3'
and o.object_name = s.segment_name
and o.object_type = s.segment_type
group by o.owner, o.object_name, o.object_type, o.status, s.buffer_pool
order by buffers;
■ Before query execution via DBLINK:
===========
DBLINK destination (remote side):
conn u2 / u2
create table tab002 as select * from dba_objects;
shu immediate
startup
select o.owner, o.object_name, o.object_type, s.buffer_pool, count (*) buffer
from dba_objects o, v $ bh b, dba_segments s
where b.objd = o.data_object_id
and o.owner = 'U 2'
and o.object_name = s.segment_name
and o.object_type = s.segment_type
group by o.owner, o.object_name, o.object_type, o.status, s.buffer_pool
order by buffers;
A record was not selected.
===========
Local side:
conn u3 / u3
select o.owner, o.object_name, o.object_type, s.buffer_pool, count (*) buffer
from dba_objects o, v $ bh b, dba_segments s
where b.objd = o.data_object_id
and o.owner = 'U 2'
and o.object_name = s.segment_name
and o.object_type = s.segment_type
group by o.owner, o.object_name, o.object_type, o.status, s.buffer_pool
order by buffers;
A record was not selected.
select o.owner, o.object_name, o.object_type, s.buffer_pool, count (*) buffer
from dba_objects o, v $ bh b, dba_segments s
where b.objd = o.data_object_id
and o.owner = 'U3'
and o.object_name = s.segment_name
and o.object_type = s.segment_type
group by o.owner, o.object_name, o.object_type, o.status, s.buffer_pool
order by buffers;
A record was not selected.
■ Query execution via DBLINK:
SQL> select count (*) from tab002 @ dbk;
COUNT (*)
----------
69263
conn u3 / u3
select o.owner, o.object_name, o.object_type, s.buffer_pool, count (*) buffer
from dba_objects o, v $ bh b, dba_segments s
where b.objd = o.data_object_id
and o.owner = 'U 2'
and o.object_name = s.segment_name
and o.object_type = s.segment_type
group by o.owner, o.object_name, o.object_type, o.status, s.buffer_pool
order by buffers;
A record was not selected. <<<<<<<<<<< Cache has no related information
select o.owner, o.object_name, o.object_type, s.buffer_pool, count (*) buffer
from dba_objects o, v $ bh b, dba_segments s
where b.objd = o.data_object_id
and o.owner = 'U3'
and o.object_name = s.segment_name
and o.object_type = s.segment_type
group by o.owner, o.object_name, o.object_type, o.status, s.buffer_pool
order by buffers;
A record was not selected. <<<<<<<<<<< Cache has no related information
===========
DBLINK destination (remote side):
select o.owner, o.object_name, o.object_type, s.buffer_pool, count (*) buffer
from dba_objects o, v $ bh b, dba_segments s
where b.objd = o.data_object_id
and o.owner = 'U 2'
and o.object_name = s.segment_name
and o.object_type = s.segment_type
group by o.owner, o.object_name, o.object_type, o.status, s.buffer_pool
order by buffers;
OWNER
-------------------------------------------------------------------- ------------------------------
OBJECT_NAME
-------------------------------------------------------------------- ------------------------------
OBJECT_TYPE BUFFER_POOL
-------------------------------------------------------------------- ------- ---------------------
BUFFERS
----------
U2
TAB 002
TABLE DEFAULT
2042 <<<<<<<<<<<<<<<<<< data got into the cache.
select o.owner, o.object_name, o.object_type, s.buffer_pool, count (*) buffer
from dba_objects o, v $ bh b, dba_segments s
where b.objd = o.data_object_id
and o.owner = 'U3'
and o.object_name = s.segment_name
and o.object_type = s.segment_type
group by o.owner, o.object_name, o.object_type, o.status, s.buffer_pool
order by buffers;
A record was not selected.
本文转自健哥的数据花园博客园博客，原文链接：http://www.cnblogs.com/gaojian/p/7575226.html，如需转载请自行联系原作者
