通过Create Directory命令创建相应的Directory之后，我们可以将目录的访问权限授予其他用户，这样其他用户就能通过外部表访问很多主机上的文件。
关于Directory的使用方法，可以参考:http://www.eygle.com/archives/2005/04/using_create_di.html
我们看一下使用外部表访问跟踪文件的例子(我的例子是用SYS用户来完成的)。
首先创建一个指向跟踪文件的Directory：
[oracle@jumper oracle]$ sqlplus "/ as sysdba"
SQL*Plus: Release 9.2.0.4.0 - Production on Tue Oct 17 22:10:05 2006
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
Connected to:
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning option
JServer Release 9.2.0.4.0 - Production
SQL> show parameter user_dump
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
user_dump_dest string /opt/oracle/admin/eygle/udump
SQL> create or replace directory udump
2 as '/opt/oracle/admin/eygle/udump';
Directory created.
SQL> col DIRECTORY_PATH for a30
SQL> select * from dba_directories;
OWNER DIRECTORY_NAME DIRECTORY_PATH
---------- ------------------------------ ------------------------------
SYS BDUMP /opt/oracle/admin/eygle/bdump
SYS UDUMP /opt/oracle/admin/eygle/udump
如果我们的某些操作需要生成跟踪文件:
SQL> alter session set sql_trace=true;
Session altered.
SQL> select count(*) from dba_users;
COUNT(*)
----------
7
SQL> alter session set sql_trace=false;
Session altered.
通过简单的脚本我们可以获得跟踪文件的名称:
SQL> set echo on
SQL> @gettrcname
SQL> SELECT d.VALUE
2 || '/'
3 || LOWER (RTRIM (i.INSTANCE, CHR (0)))
4 || '_ora_'
5 || p.spid
6 || '.trc' trace_file_name
7 FROM (SELECT p.spid
8 FROM SYS.v$mystat m, SYS.v$session s, SYS.v$process p
9 WHERE m.statistic# = 1 AND s.SID = m.SID AND p.addr = s.paddr) p,
10 (SELECT t.INSTANCE
11 FROM SYS.v$thread t, SYS.v$parameter v
12 WHERE v.NAME = 'thread'
13 AND (v.VALUE = 0 OR t.thread# = TO_NUMBER (v.VALUE))) i,
14 (SELECT VALUE
15 FROM SYS.v$parameter
16 WHERE NAME = 'user_dump_dest') d
17 /
TRACE_FILE_NAME
------------------------------------------------------------------------------------------------------------------------
/opt/oracle/admin/eygle/udump/eygle_ora_29731.trc
SQL>
然后我们可以创建外部表用以访问这个跟踪文件:
SQL> create table eygle_ora_29731 ( text varchar2(400) )
2 organization external (
3 type oracle_loader
4 default directory UDUMP
5 access parameters (
6 records delimited by newline
7 nobadfile
8 nodiscardfile
9 nologfile
10 )
11 location('eygle_ora_29731.trc')
12 ) reject limit unlimited
13 /
Table created.
最后，我们可以很容易的使用外部表访问和查询这个跟踪文件的内容:
SQL> set pagesize 100
SQL> select * from eygle_ora_29731;
TEXT
-----------------------------------------------------------------
/opt/oracle/admin/eygle/udump/eygle_ora_29731.trc
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning option
JServer Release 9.2.0.4.0 - Production
ORACLE_HOME = /opt/oracle/product/9.2.0
System name: Linux
Node name: jumper.hurray.com.cn
Release: 2.4.21-15.EL
Version: #1 Thu Apr 22 00:27:41 EDT 2004
Machine: i686
Instance name: eygle
Redo thread mounted by this instance: 1
Oracle process number: 8
Unix process pid: 29731
*** 2006-10-17 22:15:50.310
*** SESSION ID:(7.141) 2006-10-17 22:15:50.310
APPNAME mod='[email protected] (TNS V1-V3)' mh=0 act='' ah=0
=====================
PARSING IN CURSOR #1 len=32 dep=0 uid=0 oct=42 lid=0 tim=1133881396787772 hv=3943786303 ad='5ac609d4'
alter session set sql_trace=true
END OF STMT
EXEC #1:c=0
=====================
PARSING IN CURSOR #3 len=37 dep=1 uid=0 oct=3 lid=0 tim=1133881402205250 hv=3468666020 ad='5adae2d8'
select text from view$ where rowid=:1
END OF STMT
PARSE #3:c=0
EXEC #3:c=0
FETCH #3:c=0
=====================
PARSING IN CURSOR #4 len=116 dep=2 uid=0 oct=3 lid=0 tim=1133881402238727 hv=431456802 ad='5af20410'
select o.owner#
END OF STMT
PARSE #4:c=10000
EXEC #4:c=0
FETCH #4:c=0
STAT #3 id=1 cnt=1 pid=0 pos=1 obj=62 op='TABLE ACCESS BY USER ROWID VIEW$ (cr=1 r=0 w=0 time=79 us)'
=====================
PARSING IN CURSOR #1 len=30 dep=0 uid=0 oct=3 lid=0 tim=1133881402246452 hv=3198913505 ad='5adaa4ac'
select count(*) from dba_users
END OF STMT
PARSE #1:c=10000
EXEC #1:c=0
FETCH #1:c=10000
FETCH #1:c=0
STAT #1 id=1 cnt=1 pid=0 pos=1 obj=0 op='SORT AGGREGATE (cr=48 r=0 w=0 time=5276 us)'
STAT #1 id=2 cnt=7 pid=1 pos=1 obj=0 op='MERGE JOIN (cr=48 r=0 w=0 time=5250 us)'
STAT #1 id=3 cnt=7 pid=2 pos=1 obj=0 op='SORT JOIN (cr=45 r=0 w=0 time=5051 us)'
=====================
PARSING IN CURSOR #3 len=116 dep=1 uid=0 oct=3 lid=0 tim=1133881410335382 hv=431456802 ad='5af20410'
select o.owner#
END OF STMT
PARSE #3:c=0
EXEC #3:c=0
FETCH #3:c=0
STAT #1 id=4 cnt=7 pid=3 pos=1 obj=94 op='TABLE ACCESS BY INDEX ROWID PROFILE$ (cr=45 r=0 w=0 time=4881 us)'
STAT #1 id=5 cnt=127 pid=4 pos=1 obj=0 op='NESTED LOOPS (cr=44 r=0 w=0 time=3951 us)'
STAT #1 id=6 cnt=7 pid=5 pos=1 obj=0 op='NESTED LOOPS (cr=42 r=0 w=0 time=3235 us)'
STAT #1 id=7 cnt=7 pid=6 pos=1 obj=0 op='NESTED LOOPS (cr=26 r=0 w=0 time=3021 us)'
STAT #1 id=8 cnt=7 pid=7 pos=1 obj=0 op='MERGE JOIN (cr=10 r=0 w=0 time=2760 us)'
STAT #1 id=9 cnt=9 pid=8 pos=1 obj=0 op='SORT JOIN (cr=6 r=0 w=0 time=2479 us)'
STAT #1 id=10 cnt=9 pid=9 pos=1 obj=94 op='TABLE ACCESS BY INDEX ROWID PROFILE$ (cr=6 r=0 w=0 time=2284 us)'
STAT #1 id=11 cnt=163 pid=10 pos=1 obj=0 op='NESTED LOOPS (cr=5 r=0 w=0 time=1303 us)'
EXEC #3:c=0
FETCH #3:c=0
STAT #1 id=12 cnt=9 pid=11 pos=1 obj=280 op='TABLE ACCESS FULL USER_ASTATUS_MAP (cr=3 r=0 w=0 time=244 us)'
STAT #1 id=13 cnt=153 pid=11 pos=2 obj=139 op='INDEX RANGE SCAN I_PROFILE (cr=2 r=0 w=0 time=518 us)'
STAT #1 id=14 cnt=7 pid=8 pos=2 obj=0 op='SORT JOIN (cr=4 r=0 w=0 time=200 us)'
STAT #1 id=15 cnt=7 pid=14 pos=1 obj=22 op='TABLE ACCESS FULL USER$ (cr=4 r=0 w=0 time=117 us)'
STAT #1 id=16 cnt=7 pid=7 pos=2 obj=16 op='TABLE ACCESS CLUSTER TS$ (cr=16 r=0 w=0 time=199 us)'
STAT #1 id=17 cnt=7 pid=16 pos=1 obj=7 op='INDEX UNIQUE SCAN I_TS# (cr=2 r=0 w=0 time=69 us)'
STAT #1 id=18 cnt=7 pid=6 pos=2 obj=16 op='TABLE ACCESS CLUSTER TS$ (cr=16 r=0 w=0 time=166 us)'
STAT #1 id=19 cnt=7 pid=18 pos=1 obj=7 op='INDEX UNIQUE SCAN I_TS# (cr=2 r=0 w=0 time=37 us)'
STAT #1 id=20 cnt=119 pid=5 pos=2 obj=139 op='INDEX RANGE SCAN I_PROFILE (cr=2 r=0 w=0 time=342 us)'
STAT #1 id=21 cnt=7 pid=2 pos=2 obj=0 op='SORT JOIN (cr=3 r=0 w=0 time=121 us)'
EXEC #3:c=0
FETCH #3:c=0
STAT #1 id=22 cnt=1 pid=21 pos=1 obj=95 op='TABLE ACCESS FULL PROFNAME$ (cr=3 r=0 w=0 time=66 us)'
=====================
PARSING IN CURSOR #1 len=33 dep=0 uid=0 oct=42 lid=0 tim=1133881410339660 hv=4238949625 ad='5ac49f60'
alter session set sql_trace=false
END OF STMT
PARSE #1:c=0
EXEC #1:c=0
84 rows selected.
SQL>
外部表极大的简化了我们的很多管理工作。前面说过Oracle的外部表可以用来访问警告日志文件，其实Oracle的外部表可以非常灵活的被使用。
通过Create Directory命令创建相应的Directory之后，我们可以将目录的访问权限授予其他用户，这样其他用户就能通过外部表访问很多主机上的文件。
关于Directory的使用方法，可以参考:
http://www.eygle.com/archives/2005/04/using_create_di.html
我们看一下使用外部表访问跟踪文件的例子(我的例子是用SYS用户来完成的)。
首先创建一个指向跟踪文件的Directory：
[oracle@jumper oracle]$ sqlplus "/ as sysdba"
SQL*Plus: Release 9.2.0.4.0 - Production on Tue Oct 17 22:10:05 2006
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
Connected to:
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning option
JServer Release 9.2.0.4.0 - Production
SQL> show parameter user_dump
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
user_dump_dest string /opt/oracle/admin/eygle/udump
SQL> create or replace directory udump
2 as '/opt/oracle/admin/eygle/udump';
Directory created.
SQL> col DIRECTORY_PATH for a30
SQL> select * from dba_directories;
OWNER DIRECTORY_NAME DIRECTORY_PATH
---------- ------------------------------ ------------------------------
SYS BDUMP /opt/oracle/admin/eygle/bdump
SYS UDUMP /opt/oracle/admin/eygle/udump
如果我们的某些操作需要生成跟踪文件:
SQL> alter session set sql_trace=true;
Session altered.
SQL> select count(*) from dba_users;
COUNT(*)
----------
7
SQL> alter session set sql_trace=false;
Session altered.
通过简单的脚本我们可以获得跟踪文件的名称:
SQL> set echo on
SQL> @gettrcname
SQL> SELECT d.VALUE
2 || '/'
3 || LOWER (RTRIM (i.INSTANCE, CHR (0)))
4 || '_ora_'
5 || p.spid
6 || '.trc' trace_file_name
7 FROM (SELECT p.spid
8 FROM SYS.v$mystat m, SYS.v$session s, SYS.v$process p
9 WHERE m.statistic# = 1 AND s.SID = m.SID AND p.addr = s.paddr) p,
10 (SELECT t.INSTANCE
11 FROM SYS.v$thread t, SYS.v$parameter v
12 WHERE v.NAME = 'thread'
13 AND (v.VALUE = 0 OR t.thread# = TO_NUMBER (v.VALUE))) i,
14 (SELECT VALUE
15 FROM SYS.v$parameter
16 WHERE NAME = 'user_dump_dest') d
17 /
TRACE_FILE_NAME
------------------------------------------------------------------------------------------------------------------------
/opt/oracle/admin/eygle/udump/eygle_ora_29731.trc
SQL>
然后我们可以创建外部表用以访问这个跟踪文件:
SQL> create table eygle_ora_29731 ( text varchar2(400) )
2 organization external (
3 type oracle_loader
4 default directory UDUMP
5 access parameters (
6 records delimited by newline
7 nobadfile
8 nodiscardfile
9 nologfile
10 )
11 location('eygle_ora_29731.trc')
12 ) reject limit unlimited
13 /
Table created.
最后，我们可以很容易的使用外部表访问和查询这个跟踪文件的内容:
SQL> set pagesize 100
SQL> select * from eygle_ora_29731;
TEXT
-----------------------------------------------------------------
/opt/oracle/admin/eygle/udump/eygle_ora_29731.trc
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning option
JServer Release 9.2.0.4.0 - Production
ORACLE_HOME = /opt/oracle/product/9.2.0
System name: Linux
Node name: jumper.hurray.com.cn
Release: 2.4.21-15.EL
Version: #1 Thu Apr 22 00:27:41 EDT 2004
Machine: i686
Instance name: eygle
Redo thread mounted by this instance: 1
Oracle process number: 8
Unix process pid: 29731
*** 2006-10-17 22:15:50.310
*** SESSION ID:(7.141) 2006-10-17 22:15:50.310
APPNAME mod='[email protected] (TNS V1-V3)' mh=0 act='' ah=0
=====================
PARSING IN CURSOR #1 len=32 dep=0 uid=0 oct=42 lid=0 tim=1133881396787772 hv=3943786303 ad='5ac609d4'
alter session set sql_trace=true
END OF STMT
EXEC #1:c=0
=====================
PARSING IN CURSOR #3 len=37 dep=1 uid=0 oct=3 lid=0 tim=1133881402205250 hv=3468666020 ad='5adae2d8'
select text from view$ where rowid=:1
END OF STMT
PARSE #3:c=0
EXEC #3:c=0
FETCH #3:c=0
=====================
PARSING IN CURSOR #4 len=116 dep=2 uid=0 oct=3 lid=0 tim=1133881402238727 hv=431456802 ad='5af20410'
select o.owner#
END OF STMT
PARSE #4:c=10000
EXEC #4:c=0
FETCH #4:c=0
STAT #3 id=1 cnt=1 pid=0 pos=1 obj=62 op='TABLE ACCESS BY USER ROWID VIEW$ (cr=1 r=0 w=0 time=79 us)'
=====================
PARSING IN CURSOR #1 len=30 dep=0 uid=0 oct=3 lid=0 tim=1133881402246452 hv=3198913505 ad='5adaa4ac'
select count(*) from dba_users
END OF STMT
PARSE #1:c=10000
EXEC #1:c=0
FETCH #1:c=10000
FETCH #1:c=0
STAT #1 id=1 cnt=1 pid=0 pos=1 obj=0 op='SORT AGGREGATE (cr=48 r=0 w=0 time=5276 us)'
STAT #1 id=2 cnt=7 pid=1 pos=1 obj=0 op='MERGE JOIN (cr=48 r=0 w=0 time=5250 us)'
STAT #1 id=3 cnt=7 pid=2 pos=1 obj=0 op='SORT JOIN (cr=45 r=0 w=0 time=5051 us)'
=====================
PARSING IN CURSOR #3 len=116 dep=1 uid=0 oct=3 lid=0 tim=1133881410335382 hv=431456802 ad='5af20410'
select o.owner#
END OF STMT
PARSE #3:c=0
EXEC #3:c=0
FETCH #3:c=0
STAT #1 id=4 cnt=7 pid=3 pos=1 obj=94 op='TABLE ACCESS BY INDEX ROWID PROFILE$ (cr=45 r=0 w=0 time=4881 us)'
STAT #1 id=5 cnt=127 pid=4 pos=1 obj=0 op='NESTED LOOPS (cr=44 r=0 w=0 time=3951 us)'
STAT #1 id=6 cnt=7 pid=5 pos=1 obj=0 op='NESTED LOOPS (cr=42 r=0 w=0 time=3235 us)'
STAT #1 id=7 cnt=7 pid=6 pos=1 obj=0 op='NESTED LOOPS (cr=26 r=0 w=0 time=3021 us)'
STAT #1 id=8 cnt=7 pid=7 pos=1 obj=0 op='MERGE JOIN (cr=10 r=0 w=0 time=2760 us)'
STAT #1 id=9 cnt=9 pid=8 pos=1 obj=0 op='SORT JOIN (cr=6 r=0 w=0 time=2479 us)'
STAT #1 id=10 cnt=9 pid=9 pos=1 obj=94 op='TABLE ACCESS BY INDEX ROWID PROFILE$ (cr=6 r=0 w=0 time=2284 us)'
STAT #1 id=11 cnt=163 pid=10 pos=1 obj=0 op='NESTED LOOPS (cr=5 r=0 w=0 time=1303 us)'
EXEC #3:c=0
FETCH #3:c=0
STAT #1 id=12 cnt=9 pid=11 pos=1 obj=280 op='TABLE ACCESS FULL USER_ASTATUS_MAP (cr=3 r=0 w=0 time=244 us)'
STAT #1 id=13 cnt=153 pid=11 pos=2 obj=139 op='INDEX RANGE SCAN I_PROFILE (cr=2 r=0 w=0 time=518 us)'
STAT #1 id=14 cnt=7 pid=8 pos=2 obj=0 op='SORT JOIN (cr=4 r=0 w=0 time=200 us)'
STAT #1 id=15 cnt=7 pid=14 pos=1 obj=22 op='TABLE ACCESS FULL USER$ (cr=4 r=0 w=0 time=117 us)'
STAT #1 id=16 cnt=7 pid=7 pos=2 obj=16 op='TABLE ACCESS CLUSTER TS$ (cr=16 r=0 w=0 time=199 us)'
STAT #1 id=17 cnt=7 pid=16 pos=1 obj=7 op='INDEX UNIQUE SCAN I_TS# (cr=2 r=0 w=0 time=69 us)'
STAT #1 id=18 cnt=7 pid=6 pos=2 obj=16 op='TABLE ACCESS CLUSTER TS$ (cr=16 r=0 w=0 time=166 us)'
STAT #1 id=19 cnt=7 pid=18 pos=1 obj=7 op='INDEX UNIQUE SCAN I_TS# (cr=2 r=0 w=0 time=37 us)'
STAT #1 id=20 cnt=119 pid=5 pos=2 obj=139 op='INDEX RANGE SCAN I_PROFILE (cr=2 r=0 w=0 time=342 us)'
STAT #1 id=21 cnt=7 pid=2 pos=2 obj=0 op='SORT JOIN (cr=3 r=0 w=0 time=121 us)'
EXEC #3:c=0
FETCH #3:c=0
STAT #1 id=22 cnt=1 pid=21 pos=1 obj=95 op='TABLE ACCESS FULL PROFNAME$ (cr=3 r=0 w=0 time=66 us)'
=====================
PARSING IN CURSOR #1 len=33 dep=0 uid=0 oct=42 lid=0 tim=1133881410339660 hv=4238949625 ad='5ac49f60'
alter session set sql_trace=false
END OF STMT
PARSE #1:c=0
EXEC #1:c=0
84 rows selected.
SQL>
外部表极大的简化了我们的很多管理工作。