場景描述
有一個業務系統，做了OGG備庫用於統計查詢。
生產庫的維護由系統管理員負責，而備庫的日常維護由專職DBA負責。
系統廠商在對生產環境進行升級時，經常會修改數據結構。
DBA很快發現了OGG報錯，查看日誌是數據結構變更，於是向生產庫系統管理員要數據變更清單。
生產庫管理員再向系統廠商要，有時候系統廠商沒有事先準備腳本，升級時在線的部分修改沒有記錄，導致DBA不停的跟蹤錯誤信息，兩邊比對數據結構，再到備庫中進行修改，煩不勝煩。
之後，DBA在生產庫中創建了DDL觸發器，用於跟蹤數據結構變更，用來解決這個煩惱。
DDL觸發器能對數據庫中的DDL操作進行觸發，包括
實施步驟如下：
1.在生產環境的監控用戶CZFX下創建DDL操作記錄表
SQL> CREATE TABLE CZFX.T_DDL_OGG
2 (GUID VARCHAR2(50) DEFAULT SYS_GUID() PRIMARY KEY
3 ,CREATED DATE DEFAULT SYSDATE
4 ,EVENT VARCHAR2(30)
5 ,LOGIN_USER VARCHAR2(30)
6 ,OBJ_NAME VARCHAR2(30)
7 ,OBJ_OWNER VARCHAR2(30)
8 ,OBJ_TYPE VARCHAR2(30)
9 ,COLUMN_NAME VARCHAR2(30)
10 ,DDL_SQL VARCHAR2(4000)
11 ,ISDEAL VARCHAR2(1) DEFAULT '0'
12 ) TABLESPACE CZFX;
Table created
Executed in 0.031 seconds2.用SYS用戶創建DDL觸發器
（注意：其他數據庫用戶也可以創建DDL觸發器，但經測試只能捕捉到用戶自己的DDL操作）
SQL> CREATE OR REPLACE TRIGGER TRI_DBDDL
2 AFTER CREATE OR DROP OR ALTER ON DATABASE
3 WHEN (ORA_DICT_OBJ_TYPE='TABLE')
4 DECLARE
5 V_GUID VARCHAR2(50);
6 T_SQL_TXT ORA_NAME_LIST_T:=ORA_NAME_LIST_T();
7 N_COUNT PLS_INTEGER;
8 V_SQL_TXT VARCHAR2(4000);
9 BEGIN
10 V_GUID:=SYS_GUID();
11 N_COUNT:=ORA_SQL_TXT(sql_text => T_SQL_TXT);
12 FOR I IN 1..N_COUNT LOOP
13 V_SQL_TXT:=V_SQL_TXT||T_SQL_TXT(I)||CHR(10);
14 END LOOP;
15 INSERT INTO CZFX.T_DDL_OGG(GUID,CREATED,LOGIN_USER,EVENT,OBJ_NAME,OBJ_OWNER,OBJ_TYPE,DDL_SQL)
16 VALUES(V_GUID,SYSDATE,ORA_LOGIN_USER,ORA_SYSEVENT,ORA_DICT_OBJ_NAME,ORA_DICT_OBJ_OWNER,ORA_DICT_OBJ_TYPE
17 ,V_SQL_TXT);
18 FOR REC_COLUMN IN(SELECT COLUMN_NAME FROM ALL_TAB_COLUMNS WHERE OWNER=ORA_DICT_OBJ_OWNER AND TABLE_NAME=ORA_DICT_OBJ_NAME)
19 LOOP
20 IF ORA_IS_ALTER_COLUMN(REC_COLUMN.COLUMN_NAME) THEN
21 UPDATE CZFX.T_DDL_OGG SET COLUMN_NAME=LTRIM(COLUMN_NAME||','||REC_COLUMN.COLUMN_NAME,',')
22 WHERE GUID=V_GUID;
23 END IF;
24 END LOOP;
25 END;
26 /
Trigger created
Executed in 0.031 seconds這個觸發器起到了以下效果：
（1）捕捉並記錄了數據庫中任何用戶對錶（table）的create、alter、drop操作；
（2）記錄了DDL原始語句，這個非常有用，在備庫可以直接粘貼；
（3）記錄了是哪個用戶（登錄用戶）操作了哪個用戶（對象擁有者）的表
3.測試在不同數據庫用戶下做不同的DDL操作
查看日誌表
SQL> SHOW USER
User is "SYS"
SQL> CREATE TABLE TMP_DDL_SYS(COL1 VARCHAR2(1));
Table created
Executed in 0.063 seconds
SQL> select * from CZFX.T_DDL_OGG;
GUID CREATED EVENT LOGIN_USER OBJ_NAME OBJ_OWNER OBJ_TYPE COLUMN_NAME DDL_SQL ISDEAL
-------------------------------------------------- ----------- ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------ -------------------------------------------------------------------------------- ------
670898870AB51B9BE0532582290AF84C 2018/3/10 1 CREATE SYS TMP_DDL_SYS SYS TABLE CREATE TABLE TMP_DDL_SYS(COL1 VARCHAR2(1)) 0
Executed in 0.094 seconds
SQL> conn system/sys@czkf;
Connected to Oracle Database 11g Enterprise Edition Release 11.2.0.3.0
Connected as system@czkf
SQL>
SQL> CREATE TABLE TMP_DDL_SYSTEM(COL1 VARCHAR2(1));
Table created
Executed in 0.031 seconds
SQL> select * from CZFX.T_DDL_OGG;
GUID CREATED EVENT LOGIN_USER OBJ_NAME OBJ_OWNER OBJ_TYPE COLUMN_NAME DDL_SQL ISDEAL
-------------------------------------------------- ----------- ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------ -------------------------------------------------------------------------------- ------
670898870AB51B9BE0532582290AF84C 2018/3/10 1 CREATE SYS TMP_DDL_SYS SYS TABLE CREATE TABLE TMP_DDL_SYS(COL1 VARCHAR2(1)) 0
6708DEB8ECF41C9EE0532582290AF3B6 2018/3/10 1 CREATE SYSTEM TMP_DDL_SYSTEM SYSTEM TABLE CREATE TABLE TMP_DDL_SYSTEM(COL1 VARCHAR2(1)) 0
Executed in 0.11 seconds
SQL>
SQL> conn czfx/czfx@czkf;
Connected to Oracle Database 11g Enterprise Edition Release 11.2.0.3.0
Connected as czfx@czkf
SQL> CREATE TABLE TMP_DDL_CZFX(COL1 VARCHAR2(1));
Table created
Executed in 0.016 seconds
SQL> ALTER TABLE TMP_DDL_CZFX MODIFY COL1 NUMBER(2);
Table altered
Executed in 0.016 seconds
SQL> ALTER TABLE TMP_DDL_CZFX ADD COL2 VARCHAR2(20);
Table altered
Executed in 0 seconds
SQL> select * from CZFX.T_DDL_OGG;
GUID CREATED EVENT LOGIN_USER OBJ_NAME OBJ_OWNER OBJ_TYPE COLUMN_NAME DDL_SQL ISDEAL
-------------------------------------------------- ----------- ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------ -------------------------------------------------------------------------------- ------
670898870AB51B9BE0532582290AF84C 2018/3/10 1 CREATE SYS TMP_DDL_SYS SYS TABLE CREATE TABLE TMP_DDL_SYS(COL1 VARCHAR2(1)) 0
6708DEB8ECF41C9EE0532582290AF3B6 2018/3/10 1 CREATE SYSTEM TMP_DDL_SYSTEM SYSTEM TABLE CREATE TABLE TMP_DDL_SYSTEM(COL1 VARCHAR2(1)) 0
6708E1B7A1CD1F6CE0532582290A83AF 2018/3/10 1 CREATE CZFX TMP_DDL_CZFX CZFX TABLE CREATE TABLE TMP_DDL_CZFX(COL1 VARCHAR2(1)) 0
6708E1B7A1CE1F6CE0532582290A83AF 2018/3/10 1 ALTER CZFX TMP_DDL_CZFX CZFX TABLE COL1 ALTER TABLE TMP_DDL_CZFX MODIFY COL1 NUMBER(2) 0
6708E1B7A1CF1F6CE0532582290A83AF 2018/3/10 1 ALTER CZFX TMP_DDL_CZFX CZFX TABLE ALTER TABLE TMP_DDL_CZFX ADD COL2 VARCHAR2(20) 0
Executed in 0.172 seconds
SQL>
SQL> DROP TABLE TMP_DDL_CZFX PURGE;
Table dropped
Executed in 0.031 seconds
SQL> conn sys/sys@czkf AS SYSDBA;
Connected to Oracle Database 11g Enterprise Edition Release 11.2.0.3.0
Connected as sys@czkf AS SYSDBA
SQL> DROP TABLE SYSTEM.TMP_DDL_SYSTEM PURGE;
Table dropped
Executed in 0.047 seconds
SQL> DROP TABLE TMP_DDL_SYS PURGE;
Table dropped
Executed in 0.032 seconds
SQL> select * from CZFX.T_DDL_OGG ORDER BY CREATED;
GUID CREATED EVENT LOGIN_USER OBJ_NAME OBJ_OWNER OBJ_TYPE COLUMN_NAME DDL_SQL ISDEAL
-------------------------------------------------- ----------- ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------ -------------------------------------------------------------------------------- ------
670898870AB51B9BE0532582290AF84C 2018/3/10 1 CREATE SYS TMP_DDL_SYS SYS TABLE CREATE TABLE TMP_DDL_SYS(COL1 VARCHAR2(1)) 0
6708DEB8ECF41C9EE0532582290AF3B6 2018/3/10 1 CREATE SYSTEM TMP_DDL_SYSTEM SYSTEM TABLE CREATE TABLE TMP_DDL_SYSTEM(COL1 VARCHAR2(1)) 0
6708E1B7A1CD1F6CE0532582290A83AF 2018/3/10 1 CREATE CZFX TMP_DDL_CZFX CZFX TABLE CREATE TABLE TMP_DDL_CZFX(COL1 VARCHAR2(1)) 0
6708E1B7A1CE1F6CE0532582290A83AF 2018/3/10 1 ALTER CZFX TMP_DDL_CZFX CZFX TABLE COL1 ALTER TABLE TMP_DDL_CZFX MODIFY COL1 NUMBER(2) 0
6708E1B7A1CF1F6CE0532582290A83AF 2018/3/10 1 ALTER CZFX TMP_DDL_CZFX CZFX TABLE ALTER TABLE TMP_DDL_CZFX ADD COL2 VARCHAR2(20) 0
6708E1B7A1D01F6CE0532582290A83AF 2018/3/10 1 DROP CZFX TMP_DDL_CZFX CZFX TABLE DROP TABLE TMP_DDL_CZFX PURGE 0
6708E56C22271F9BE0532582290AF4DB 2018/3/10 1 DROP SYS TMP_DDL_SYSTEM SYSTEM TABLE DROP TABLE SYSTEM.TMP_DDL_SYSTEM PURGE 0
6708E56C22281F9BE0532582290AF4DB 2018/3/10 1 DROP SYS TMP_DDL_SYS SYS TABLE DROP TABLE TMP_DDL_SYS PURGE 0
8 rows selected
Executed in 0.234 seconds接下來就通過各種方式通知DBA就可以了，DBA對新增的DDL操作在備庫中進行處理，並把記錄刪掉或標記爲已處理。
這樣就完成了一個OGG的DDL操作自動管理機制，本人部署完這套東西后，添加了短信提醒功能，在GoldenGate主庫出現異常時能夠在不聯繫主庫管理員的情況下迅速恢復OGG運行，收益匪淺。
當然，DDL觸發器還可以用於跟蹤其他數據庫對象的DDL操作，支持的DDL命令有以下這些：
