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测试一把

原创 IT综合 作者:OmarChina 时间:2007-09-03 13:27:04 0 删除 编辑
alter session set events '10046 trace name context forever,levle 8';[@more@]

SQL> create table t as select * from dba_objects;

Table created.

SQL> insert into t select * from t;

55867 rows created.

SQL> /

111734 rows created.

SQL> commit;

Commit complete.

SQL> /

Commit complete.

SQL> insert into t select * from t;

223468 rows created.

SQL> commit;

Commit complete.

SQL> show parameter db_file_mult

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_file_multiblock_read_count integer 16
SQL> alter session set events '10046 trace name context forever,level 8';

Session altered.

SQL> alter session set db_file_multiblock_read_count=256;

Session altered.

SQL> select count(*) from t;

COUNT(*)
----------
446936

SQL> exit
Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - Production
With the Partitioning, OLAP and Data Mining options
[oracle@tsdb01-shcd ~]$ cd /u01/app/oracle/admin/southdb/udump/
[oracle@tsdb01-shcd udump]$ ls
southdb_ora_19628.trc

查看相应的trace文件,里面应有如下('db file scattered read)内容:
WAIT #1: nam='db file scattered read' ela= 0 p1=1 p2=4986 p3=128

p3就是Oracle一次IO的块数。

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