hi,list friends
I am looking at rac performance and see tomas' paper, and i did a test:
http://asktom.oracle.com/~tkyte/9iSeminar/img17.html
My platform:
Dell 6650 with 4*1.4G cpu and 4G memory on both nodes with 9.2 RAC and RDAS
2.1 OS.During this time, the server is quite idle.
First i did a full table scan of some table in node1:
08:02:12 SQL> select count(*) from pdtviewcount;
COUNT(*)
----------
808550
Elapsed: 00:00:01.09
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=4 Card=1)
1 0 SORT (AGGREGATE)
2 1 INDEX (FAST FULL SCAN) OF 'PK_COUNT' (UNIQUE) (Cost=4 Ca
rd=8168)
Statistics
----------------------------------------------------------
193 recursive calls
2 db block gets
1792 consistent gets
1728 physical reads
188 redo size
381 bytes sent via SQL*Net to client
503 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
6 sorts (memory)
0 sorts (disk)
1 rows processed
As you see, the full index scan is nearly all physical read, and it takes
about 1 second.
And now i did a second count from the second node 2:
08:08:54 SQL> select count(*) from pdtviewcount;
COUNT(*)
----------
808550
Elapsed: 00:00:06.32
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=4 Card=1)
1 0 SORT (AGGREGATE)
2 1 INDEX (FAST FULL SCAN) OF 'PK_COUNT' (UNIQUE) (Cost=4 Ca
rd=8168)
Statistics
----------------------------------------------------------
192 recursive calls
0 db block gets
1735 consistent gets
1056 physical reads
0 redo size
381 bytes sent via SQL*Net to client
503 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
6 sorts (memory)
0 sorts (disk)
1 rows processed
As you see, it is mostly get from the physical disk, not the interconnect, and
in the first node, it takes about 1 second while doing physical read, but in the
second case, less physical io, but much slower(as you see ,it is 6.5 second!).
So how about RAC advantage? Please share your opinion.
Regards
zhu chao
Eachnet DBA
86-21-32174588-667
[EMAIL PROTECTED]
www.happyit.net
www.cnoug.org(Chinese Oracle User Group)
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