今天同事提出了一個問題：
使用數據泵expdp導出1個schema，有個表主鍵是觸發器自增的id，導入測試庫測試時，發現表里的數據比自增序列的值要大。導致插入數據報錯。
最終結論是：
由於數據庫先進行序列導出，然后再進行表數據導出。然后在導出的過程中，該表一直有插入操作，最終導致了這種差異。
解決方法：
重建觸發器中的序列，讓序列的開始值為表主鍵最大值+1。
下面我構造實驗完整演示下這種場景。
1.准備測試環境
需要建立測試表，序列，觸發器和模擬業務插入數據的存儲過程。 以下是實際的創建語句：--在測試用戶jingyu下創建測試表book2
drop table book2 purge;
create table book2(
bookId number(10) primary key,
name varchar2(20)
);
--創建序列
drop sequence book2_seq;
create sequence book2_seq start with 1 increment by 1;
--創建觸發器
create or replace trigger book2_trigger
before insert on book2
for each row
begin
select book2_seq.nextval into :new.bookId from dual;
end ;
/
--創建實現循環添加數據的存儲過程
/*
--存儲過程中使用需要顯示賦權
grant execute on dbms_lock to jingyu;
*/
create or replace procedure proc_insert_book2 is
begin
loop
insert into book2(name) values ('xx');
commit;
dbms_lock.sleep(1);
end loop;
end;
/
2.開始模擬該表不斷插入
由於我這里實際使用的是死循環，所以只要開始執行存儲過程，每秒都會向測試表插入1條測試數據，直到手工停止。
--執行該存儲過程
exec proc_insert_book2;
--查詢表的數量，確認是每秒多一條數據
select count(*) from book2;
3.進行數據泵導出操作
確認導出目錄，編寫expdp導出語句，最終將jingyu這個schema導出。實際命令如下：--expdp 導出
create or replace directory jy as '/opt/app/orabak/';
expdp jingyu/jingyu directory=jy dumpfile=jingyu.dmp schemas=jingyu
實際執行導出的輸出如下：
[oracle@jyrac1 orabak]$ expdp jingyu/jingyu directory=jy dumpfile=jingyu.dmp schemas=jingyu
Export: Release 11.2.0.4.0 - Production on Thu Jun 8 17:08:29 2017
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Data Mining and Real Application Testing options
Starting "JINGYU"."SYS_EXPORT_SCHEMA_05": jingyu/******** directory=jy dumpfile=jingyu.dmp schemas=jingyu
Estimate in progress using BLOCKS method...
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 10.12 MB
Processing object type SCHEMA_EXPORT/USER
Processing object type SCHEMA_EXPORT/SYSTEM_GRANT
Processing object type SCHEMA_EXPORT/ROLE_GRANT
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Processing object type SCHEMA_EXPORT/TABLESPACE_QUOTA
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
Processing object type SCHEMA_EXPORT/SEQUENCE/SEQUENCE
Processing object type SCHEMA_EXPORT/TABLE/TABLE
Processing object type SCHEMA_EXPORT/TABLE/COMMENT
Processing object type SCHEMA_EXPORT/PROCEDURE/PROCEDURE
Processing object type SCHEMA_EXPORT/PROCEDURE/ALTER_PROCEDURE
Processing object type SCHEMA_EXPORT/TABLE/INDEX/INDEX
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type SCHEMA_EXPORT/TABLE/TRIGGER
Processing object type SCHEMA_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
. . exported "JINGYU"."T2" 6.649 MB 100000 rows
. . exported "JINGYU"."SYS_EXPORT_SCHEMA_01" 142.0 KB 1195 rows
. . exported "JINGYU"."SYS_EXPORT_SCHEMA_02" 142.2 KB 1196 rows
. . exported "JINGYU"."SYS_EXPORT_SCHEMA_03" 142.6 KB 1198 rows
. . exported "JINGYU"."SYS_EXPORT_SCHEMA_04" 149.7 KB 1201 rows
. . exported "JINGYU"."T_OLD" 160.8 KB 20000 rows
. . exported "JINGYU"."T" 82.94 KB 10000 rows
. . exported "JINGYU"."T_NOLOG" 51.53 KB 5998 rows
. . exported "JINGYU"."BOOK" 5.421 KB 2 rows
. . exported "JINGYU"."BOOK2" 6.734 KB 123 rows
. . exported "JINGYU"."EMP" 8.562 KB 14 rows
. . exported "JINGYU"."T1" 11.75 KB 100 rows
Master table "JINGYU"."SYS_EXPORT_SCHEMA_05" successfully loaded/unloaded
******************************************************************************
Dump file set for JINGYU.SYS_EXPORT_SCHEMA_05 is:
/opt/app/orabak/jingyu.dmp
Job "JINGYU"."SYS_EXPORT_SCHEMA_05" successfully completed at Thu Jun 8 17:10:26 2017 elapsed 0 00:01:36
4.進行數據泵導入操作
將上一步的導出文件，導入到另一個新建的測試用戶jingyu2下。實際命令如下：--創建測試用戶並賦予一定的權限
create user jingyu2 identified by jingyu2 default tablespace dbs_d_jingyu;
grant connect, resource to jingyu2;
--impdp 導入到用戶jingyu2
impdp jingyu/jingyu directory=jy dumpfile=jingyu.dmp REMAP_SCHEMA=jingyu:jingyu2
實際執行導入的輸出如下：
[oracle@jyrac1 orabak]$ impdp jingyu/jingyu directory=jy dumpfile=jingyu.dmp REMAP_SCHEMA=jingyu:jingyu2
Import: Release 11.2.0.4.0 - Production on Thu Jun 8 17:11:21 2017
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Data Mining and Real Application Testing options
Master table "JINGYU"."SYS_IMPORT_FULL_01" successfully loaded/unloaded
Starting "JINGYU"."SYS_IMPORT_FULL_01": jingyu/******** directory=jy dumpfile=jingyu.dmp REMAP_SCHEMA=jingyu:jingyu2
Processing object type SCHEMA_EXPORT/USER
ORA-31684: Object type USER:"JINGYU2" already exists
Processing object type SCHEMA_EXPORT/SYSTEM_GRANT
Processing object type SCHEMA_EXPORT/ROLE_GRANT
Processing object type SCHEMA_EXPORT/DEFAULT_ROLE
Processing object type SCHEMA_EXPORT/TABLESPACE_QUOTA
Processing object type SCHEMA_EXPORT/PRE_SCHEMA/PROCACT_SCHEMA
Processing object type SCHEMA_EXPORT/SEQUENCE/SEQUENCE
Processing object type SCHEMA_EXPORT/TABLE/TABLE
Processing object type SCHEMA_EXPORT/TABLE/TABLE_DATA
. . imported "JINGYU2"."T2" 6.649 MB 100000 rows
. . imported "JINGYU2"."SYS_EXPORT_SCHEMA_01" 142.0 KB 1195 rows
. . imported "JINGYU2"."SYS_EXPORT_SCHEMA_02" 142.2 KB 1196 rows
. . imported "JINGYU2"."SYS_EXPORT_SCHEMA_03" 142.6 KB 1198 rows
. . imported "JINGYU2"."SYS_EXPORT_SCHEMA_04" 149.7 KB 1201 rows
. . imported "JINGYU2"."T_OLD" 160.8 KB 20000 rows
. . imported "JINGYU2"."T" 82.94 KB 10000 rows
. . imported "JINGYU2"."T_NOLOG" 51.53 KB 5998 rows
. . imported "JINGYU2"."BOOK" 5.421 KB 2 rows
. . imported "JINGYU2"."BOOK2" 6.734 KB 123 rows
. . imported "JINGYU2"."EMP" 8.562 KB 14 rows
. . imported "JINGYU2"."T1" 11.75 KB 100 rows
Processing object type SCHEMA_EXPORT/TABLE/COMMENT
Processing object type SCHEMA_EXPORT/PROCEDURE/PROCEDURE
Processing object type SCHEMA_EXPORT/PROCEDURE/ALTER_PROCEDURE
ORA-39082: Object type ALTER_PROCEDURE:"JINGYU2"."PRO_SELECT" created with compilation warnings
ORA-39082: Object type ALTER_PROCEDURE:"JINGYU2"."PROC_INSERT_BOOK2" created with compilation warnings
Processing object type SCHEMA_EXPORT/TABLE/INDEX/INDEX
Processing object type SCHEMA_EXPORT/TABLE/CONSTRAINT/CONSTRAINT
Processing object type SCHEMA_EXPORT/TABLE/INDEX/STATISTICS/INDEX_STATISTICS
Processing object type SCHEMA_EXPORT/TABLE/TRIGGER
Processing object type SCHEMA_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Job "JINGYU"."SYS_IMPORT_FULL_01" completed with 3 error(s) at Thu Jun 8 17:11:52 2017 elapsed 0 00:00:26
導入完成，但存在一些警告，與本實驗有關的只有"JINGYU2"."PROC_INSERT_BOOK2" 編輯警告需要處理，在下面的步驟中詳細說明。
5.問題現象重現並解決
**問題現象重現：** 查詢到表最大的BOOKID大於序列的當前值，具體情況如下：SQL> select max(BOOKID) from book2;
MAX(BOOKID)
-----------
505
SQL> select book2_seq.currval from dual;
select book2_seq.currval from dual
*
ERROR at line 1:
ORA-08002: sequence BOOK2_SEQ.CURRVAL is not yet defined in this session
SQL> select book2_seq.nextval from dual;
NEXTVAL
----------
341
導入的存儲過程存在編譯警告的問題，排查原因是權限問題，需要先處理下：
--執行存儲過程報錯對象無效
SQL> exec proc_insert_book2
BEGIN proc_insert_book2; END;
*
ERROR at line 1:
ORA-06550: line 1, column 7:
PLS-00905: object JINGYU2.PROC_INSERT_BOOK2 is invalid
ORA-06550: line 1, column 7:
PL/SQL: Statement ignored
--重新編譯存儲過程依然有錯誤
SQL> alter procedure proc_insert_book2 compile;
Warning: Procedure altered with compilation errors.
--顯示具體的錯誤
SQL> show errors
Errors for PROCEDURE PROC_INSERT_BOOK2:
LINE/COL ERROR
-------- -----------------------------------------------------------------
6/5 PL/SQL: Statement ignored
6/5 PLS-00201: identifier 'DBMS_LOCK' must be declared
--根據錯誤提示，賦權解決
SQL> show user
USER is "SYS"
SQL> grant execute on dbms_lock to jingyu2;
Grant succeeded.
--再次編譯成功
SQL> alter procedure proc_insert_book2 compile;
Procedure altered.
編譯存儲過程成功后，執行它模擬插入數據，意料之中的會報錯：
SQL> exec proc_insert_book2
BEGIN proc_insert_book2; END;
*
ERROR at line 1:
ORA-00001: unique constraint (JINGYU2.SYS_C0011351) violated
ORA-06512: at "JINGYU2.PROC_INSERT_BOOK2", line 4
ORA-06512: at line 1
--查詢測試表主鍵bookid的最大值
SQL> select max(bookid) from book2;
MAX(BOOKID)
-----------
505
重新創建序列，序列開始值設置為MAX(BOOKID)+1，再次執行就可以正常插入了。
重新創建序列的語句如下：
--重新創建序列
drop sequence book2_seq;
create sequence book2_seq start with 506 increment by 1;
至此，整個實驗完成。