?span lang="EN-US">SQL*PLUS中，当你成功的执行一个DML语句Q比?/span>
SELECT
,
DELETE
,
UPDATE
,
INSERTQ你
可以通过SQL优化器和语句的执行统计自动的获得一份报告。这份报告对于DML语句的性能监控和调优都是很有用处的。这份报告就是本文要讲的AUTOTRACE 报告??xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /?>
配置AUTOTRACE报告QConfiguring the AUTOTRACE ReportQ?/span>
你可以通过以下?span lang="EN-US">AUTOTRACEpȝ变量来配|AUTOTRACE报告. 如下表：
Table AUTOTRACE Settings
|
AUTOTRACE Setting
|
Result
|
|
SET AUTOTRACE OFF
|
不能获得
AUTOTRACE报告
. q是默认?
|
|
SET AUTOTRACE ON EXPLAIN
|
仅仅昄优化器执行计划的
AUTOTRACE
报告
|
|
SET AUTOTRACE ON STATISTICS
|
仅仅昄SQL语句执行的统计结果的
AUTOTRACE
报告
|
|
SET AUTOTRACE ON
|
包括上面两项内容?span lang="EN-US">AUTOTRACE报告
|
|
SET AUTOTRACE TRACEONLY
|
?/span>
SET
AUTOTRACE
ONcM
,所有的l计和数据都在，但不可以打印
|
其实Q^时我们应该较多的是SET AUTOTRACE ON 、SET AUTOTRACE OFF,谁会在乎多看一点AUTOTRACE报告呢！
J
安装AUTOTRACE报告QSetups Required for the AUTOTRACE ReportQ?/span>
要用q个Ҏ，用户必须被赋?span lang="EN-US">PLUSTRACE角色Q而PLUSTRACE角色需要DBA来赋予。另外，该用户必d建PLAN_TABLE表?o:p>
I.
首先创徏PLUSTRACE角色q且赋给DBAQ?o:p>
CONNECT sys/sys’s password AS SYSDBA
@$ORACLE_HOME/sqlplus/admin/plustrce.sql
II.
赋权限给用户
CONNECT / AS SYSDBA
GRANT PLUSTRACE TO USERQ预赋权的用户名Q?
q样Q就可以在该用户下设|?span lang="EN-US">AUTOTRACE报告的显CZ否了?/span>
AUTOTRACE报告中涉及到的两个方面的内容
IQ?span style="FONT: 7pt 'Times New Roman'">
SQL语句的执行计?o:p>
执行计划是SQL优化器执行语句的查询执行序Q每一行的执行计划都会有个行号Q这个行hq箋?o:p>
IIQ?span style="FONT: 7pt 'Times New Roman'">
SQL语句的数据库l计
数据库统计是服务器记录的执行当前的这条语句所需要的pȝ资源{，主要包括下表的内?span lang="EN-US">
|
Database Statistic Name
|
Description
|
|
recursive calls
|
Number of recursive calls generated at both the user and system level. Oracle maintains tables used for internal processing. When Oracle needs to make a change to these tables, it internally generates an internal SQL statement, which in turn generates a recursive call.
|
|
db block gets
|
Number of times a CURRENT block was requested.
|
|
consistent gets
|
Number of times a consistent read was requested for a block.
|
|
physical reads
|
Total number of data blocks read from disk. This number equals the value of "physical reads direct" plus all reads into buffer cache.
|
|
redo size
|
Total amount of redo generated in bytes.
|
|
bytes sent via SQL*Net to client
|
Total number of bytes sent to the client from the foreground processes.
|
|
bytes received via SQL*Net from client
|
Total number of bytes received from the client over Oracle Net.
|
|
SQL*Net roundtrips to/from client
|
Total number of Oracle Net messages sent to and received from the client.
|
|
sorts (memory)
|
Number of sort operations that were performed completely in memory and did not require any disk writes.
|
|
sorts (disk)
|
Number of sort operations that required at least one disk write.
|
|
rows processed
|
Number of rows processed during the operation.
|
单用的例子Q?span lang="EN-US">
SQL> show user
USER is "SYS"
Q注Q当前是sysdba用户Q?o:p>
Q注Q创?span lang="EN-US">PLUSTRACE角色q且赋给DBAQ?/span>
SQL> start $ORACLE_HOME/sqlplus/admin/plustrce.sql
Q注Q?span lang="EN-US">start {h于@Q?o:p>
SQL> drop role plustrace;
drop role plustrace
*
ERROR at line 1:
ORA-01919: role 'PLUSTRACE' does not exist
SQL> create role plustrace;
Role created.
SQL>
SQL> grant select on v_$sesstat to plustrace;
Grant succeeded.
SQL> grant select on v_$statname to plustrace;
Grant succeeded.
SQL>
SQL> grant select on v_$session to plustrace;
Grant succeeded.
SQL> grant plustrace to dba with admin option;
Grant succeeded.
SQL>
SQL> set echo off
Q注Q赋角色plustracel所需用户Q这里用hbillQ?o:p>
SQL> grant plustrace to bill;
Grant succeeded.
Q注Q接下来Q用bill用户q接Q测试AUTOTRACEQ?o:p>
SQL> connect bill/bill’s password;
Connected.
SQL> show user
USER is "BILL"
(注：Z看的清楚些，建立一个测试的表testQ然后察看AUTOTRACE报告)
SQL> create table test(id number(1));
Table created.
SQL> insert into test values(1);
1 row created.
SQL> /
1 row created.
SQL> /
1 row created.
SQL> /
1 row created.
SQL> commit;
Commit complete.
SQL> select * from test;
ID
----------
1
1
1
1
SQL> set AUTOTRACE on
SQL> select * from test;
ID
----------
1
1
1
1
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE
1 0 TABLE ACCESS (FULL) OF 'TEST'
Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
4 consistent gets
0 physical reads
0 redo size
547 bytes sent via SQL*Net to client
655 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
4
rows processed
上面我们可以看刎ͼ当你讄?span lang="EN-US">set AUTOTRACE on后，执行相应的DML语句Q就会有相应的AUTOTRACE报告出现了。当Ӟ我们的这U设|是sessionU别的。这P我们可以根据AUTOTRACE报告Ҏ们执行的DML语句q行分析和调优了Q?br />
转自Q?a >http://dev.csdn.net/develop/article/23/23430.shtm
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