今天客户说了一个我感觉有意思的需求:在一个库上的一张表记录所有库的ddl操作,实现方式：在一个库上建立表和触发器,其他库上通过dblink+同义词+触发器实现ddl操作记录到远程的表中.他当时写了一个触发器,但是有错误,想让我协助解决.在我们的一起努力下,解决了该触发器在dblink同义词的库上出错的问题.我这里测试使用的是10g的库做为存储所有库的ddl记录的库,11g库做为一个通过dblink插入ddl操作记录的库.
在10g数据库库中操作
1.创建记录ddl操作表
SQL> conn chf/xifenfei Connected. SQL> create table t_ddl_audit( 2 db_name varchar2(30), 3 login_user varchar2(30), 4 ddl_time date, 5 ip_address varchar2(20), 6 audsid varchar2(20), 7 schema_user varchar2(30), 8 schema_object varchar2(40), 9 login_tool varchar2(40), 10 os_user varchar2(40), 11 ddl_sql varchar2(4000)); Table created.
2.创建触发器
SQL> create or replace trigger tri_ddl_audit
2 before ddl on database
3 declare
4 n number;
5 str_stmt varchar2(4000);
6 sql_text ora_name_list_t;
7 l_trace number;
8 v_module varchar2(50);
9 v_action varchar2(50);
10 str_session v$session%rowtype;
11 begin
12 n := ora_sql_txt(sql_text);
13 for i in 1 .. n loop
14 str_stmt := substr(str_stmt || sql_text(i), 1, 3000);
15 end loop;
16 dbms_application_info.READ_MODULE(v_module, v_action);
17 INSERT INTO chf.t_ddl_audit
18 (db_name,
19 login_user,
20 ddl_time,
21 ip_address,
22 audsid,
23 schema_user,
24 schema_object,
25 login_tool,
26 os_user,
27 ddl_sql)
28 VALUES
29 (sys_context('USERENV', 'db_name'),
30 ora_login_user,
31 SYSDATE,
32 sys_context('USERENV', 'IP_ADDRESS'),
33 userenv('SESSIONID'),
34 ora_dict_obj_owner,
35 ora_dict_obj_name,
36 v_module,
37 sys_context('userenv', 'os_user'),
38 str_stmt);
39 exception
40 when no_data_found then
41 null;
42 end;
43 /
Trigger created.
3.测试触发器
SQL> conn chf/xifenfei Connected. SQL> create table t_xff as select * from dba_tables where rownum=1; Table created. SQL> select db_name,login_user,ddl_sql from t_ddl_audit; DB_NAME LOGIN_USER ------------------------------ ------------------------------ DDL_SQL ----------------------------------------------------------------- XFF CHF create table t_xff as select * from dba_tables where rownum=1
在11g数据库中操作
1.创建dblink和同义词
SQL> create database link "ora10g_dblink" 2 connect to chf 3 identified by "xifenfei" 4 using 'ora10g'; Database link created. SQL> create synonym t_ddl_audit for t_ddl_audit@ora10g_dblink; Synonym created.
2.第一次创建触发器
SQL> create or replace trigger tri_ddl_audit
2 before ddl on database
3 declare
4 n number;
5 str_stmt varchar2(4000);
6 sql_text ora_name_list_t;
7 l_trace number;
8 v_module varchar2(50);
9 v_action varchar2(50);
10 str_session v$session%rowtype;
11 begin
12 n := ora_sql_txt(sql_text);
13 for i in 1 .. n loop
14 str_stmt := substr(str_stmt || sql_text(i), 1, 3000);
15 end loop;
16 dbms_application_info.READ_MODULE(v_module, v_action);
17 INSERT INTO t_ddl_audit
18 (db_name,
19 login_user,
20 ddl_time,
21 ip_address,
22 audsid,
23 schema_user,
24 schema_object,
25 login_tool,
26 os_user,
27 ddl_sql)
28 VALUES
29 (sys_context('USERENV', 'db_name'),
30 ora_login_user,
31 SYSDATE,
32 sys_context('USERENV', 'IP_ADDRESS'),
33 userenv('SESSIONID'),
34 ora_dict_obj_owner,
35 ora_dict_obj_name,
36 v_module,
37 sys_context('userenv', 'os_user'),
38 str_stmt);
39 exception
40 when no_data_found then
41 null;
42 end;
43 /
Trigger created.
3.测试触发器
SQL> create table t_xff as select * from dba_objects where rownum<10;
create table t_xff as select * from dba_objects where rownum<10
*
ERROR at line 1:
ORA-00604: error occurred at recursive SQL level 1
ORA-02070: database does not support in this context
ORA-06512: at line 15
出现ORA-02070错误,估计是类此sys_context(‘userenv’, ‘os_user’)导致。
4.第二次创建触发器
SQL> create or replace trigger tri_ddl_audit
2 before ddl on database
3 declare
4 n number;
5 str_stmt varchar2(4000);
6 sql_text ora_name_list_t;
7 l_trace number;
8 v_module varchar2(50);
9 v_action varchar2(50);
10 v_db_name varchar2(50);
11 v_ip_addr varchar2(50);
12 v_os varchar2(50);
13 v_session_id varchar2(50);
14 str_session v$session%rowtype;
15 begin
16 n := ora_sql_txt(sql_text);
17 for i in 1 .. n loop
18 str_stmt := substr(str_stmt || sql_text(i), 1, 3000);
19 end loop;
20 dbms_application_info.READ_MODULE(v_module, v_action);
21 v_db_name :=sys_context('USERENV', 'db_name');
22 v_ip_addr :=sys_context('USERENV', 'IP_ADDRESS');
23 v_os:=sys_context('userenv', 'os_user');
24 v_session_id:=userenv('SESSIONID');
25 INSERT INTO t_ddl_audit
26 (db_name,
27 login_user,
28 ddl_time,
29 ip_address,
30 audsid,
31 schema_user,
32 schema_object,
33 login_tool,
34 os_user,
35 ddl_sql)
36 VALUES
37 (v_db_name,
38 ora_login_user,
39 SYSDATE,
40 v_ip_addr,
41 v_session_id,
42 ora_dict_obj_owner,
43 ora_dict_obj_name,
44 v_module,
45 v_os,
46 str_stmt);
47 exception
48 when no_data_found then
49 null;
50 end;
51 /
Trigger created.
5.继续测试触发器
SQL> drop table t3; drop table t3 * ERROR at line 1: ORA-00604: error occurred at recursive SQL level 1 ORA-02069: global_names parameter must be set to TRUE for this operation ORA-06512: at line 23
根据ORA-02069,查询资料发现是通过dblink插入数据使用了变量和常量的方式混合使用导致该错误,修改触发器全部使用变量方式
6.第三次创建触发器
SQL> create or replace trigger tri_ddl_audit
2 before ddl on database
3 declare
4 n number;
5 str_stmt varchar2(4000);
6 sql_text ora_name_list_t;
7 l_trace number;
8 v_module varchar2(50);
9 v_action varchar2(50);
10 v_db_name varchar2(50);
11 v_ip_addr varchar2(50);
12 v_os varchar2(50);
13 v_session_id varchar2(50);
14 v_loginuser varchar2(50);
15 v_obj_name varchar2(50);
16 v_owner varchar2(50);
17 str_session v$session%rowtype;
18 begin
19 n := ora_sql_txt(sql_text);
20 for i in 1 .. n loop
21 str_stmt := substr(str_stmt || sql_text(i), 1, 3000);
22 end loop;
23 dbms_application_info.READ_MODULE(v_module, v_action);
24 v_db_name :=sys_context('USERENV', 'db_name');
25 v_ip_addr :=sys_context('USERENV', 'IP_ADDRESS');
26 v_os:=sys_context('userenv', 'os_user');
27 v_session_id:=userenv('SESSIONID');
28 v_loginuser:= ora_login_user;
29 v_owner:=ora_dict_obj_owner;
30 v_obj_name:=ora_dict_obj_name;
31 INSERT INTO t_ddl_audit
32 (db_name,
33 login_user,
34 ddl_time,
35 ip_address,
36 audsid,
37 schema_user,
38 schema_object,
39 login_tool,
40 os_user,
41 ddl_sql)
42 VALUES
43 (v_db_name,
44 v_loginuser,
45 SYSDATE,
46 v_ip_addr,
47 v_session_id,
48 v_owner,
49 v_obj_name,
50 v_module,
51 v_os,
52 str_stmt);
53 exception
54 when no_data_found then
55 null;
56 end;
57 /
Trigger created.
7.测试触发器
SQL> create table t_xff11 as select * from dba_tables where rownum<10; Table created. SQL> select db_name,login_user,ddl_sql from t_ddl_audit; DB_NAME LOGIN_USER ------------------------------ ------------------------------ DDL_SQL ----------------------------------------------------------------- ora11g CHF create table t_xff11 as select * from dba_tables where rownum<10 XFF CHF create table t_xff as select * from dba_tables where rownum=1
补充说明
这个方案个人感觉是一个实验室中的方案,在实际的生成环境中很难应用上
1.trigger记录ddl操作本身效率不高
2.如果某个库不能访问存储ddl操作的表的数据库,将导致该数据库所有ddl操作hang住,从而可能使得该数据库hang住的风险.
