數(shù)據(jù)庫(kù)中數(shù)據(jù)泵避免個(gè)別表數(shù)據(jù)的導(dǎo)出方法是什么

本篇內(nèi)容介紹了“數(shù)據(jù)庫(kù)中數(shù)據(jù)泵避免個(gè)別表數(shù)據(jù)的導(dǎo)出方法是什么”的有關(guān)知識(shí)，在實(shí)際案例的操作過(guò)程中，不少人都會(huì)遇到這樣的困境，接下來(lái)就讓小編帶領(lǐng)大家學(xué)習(xí)一下如何處理這些情況吧！希望大家仔細(xì)閱讀，能夠?qū)W有所成！

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對(duì)于數(shù)據(jù)泵EXPDP/IMPDP而言，功能比普通EXP/IMP功能要強(qiáng)的多，因此也可以實(shí)現(xiàn)一些普通導(dǎo)出導(dǎo)入工具很難完成的工作。

比如今天碰到的這個(gè)問(wèn)題，要導(dǎo)出一些表，但是其中個(gè)別表只導(dǎo)出結(jié)構(gòu)而不導(dǎo)出數(shù)據(jù)。

SQL> conn test/test
Connected.
SQL> set pages 100 lines 120
SQL> select count(*) from t;

COUNT(*)
----------
23

SQL> select count(*) from tt;

COUNT(*)
----------
72

SQL> exit
Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options
[oracle@yans1 ~]$ expdp test/test directory=d_output dumpfile=t_tt1.dp tables=(t,tt)

Export: Release 10.2.0.3.0 - 64bit Production on星期二, 25 8月, 2009 16:04:58

Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options
Starting "TEST"."SYS_EXPORT_TABLE_01": test/******** directory=d_output dumpfile=t_tt1.dp tables=(t,tt)
Estimate in progress using BLOCKS method...
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 256 KB
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
. . exported "TEST"."T" 5.953 KB 23 rows
. . exported "TEST"."TT" 6.421 KB 72 rows
Master table "TEST"."SYS_EXPORT_TABLE_01" successfully loaded/unloaded
******************************************************************************
Dump file set for TEST.SYS_EXPORT_TABLE_01 is:
/home/oracle/t_tt1.dp
Job "TEST"."SYS_EXPORT_TABLE_01" successfully completed at 16:05:02

用T和TT表作為例子，分別代表需要導(dǎo)出結(jié)構(gòu)的表和同時(shí)包含結(jié)構(gòu)和數(shù)據(jù)的表。

這個(gè)需求對(duì)于普通的EXP/IMP來(lái)說(shuō)，只能通過(guò)兩次導(dǎo)出操作來(lái)完成，一次導(dǎo)出包含數(shù)據(jù)的表，另一個(gè)通過(guò)執(zhí)行ROWS=N導(dǎo)出僅需要結(jié)構(gòu)的表。

對(duì)于EXPDP來(lái)說(shuō)，同樣可以使用類似的方法，參數(shù)CONTENT控制導(dǎo)出的結(jié)構(gòu)、數(shù)據(jù)還是全部：

[oracle@yans1 ~]$ expdp test/test directory=d_output dumpfile=t_tt2.dp tables=(t,tt) content=metadata_only

Export: Release 10.2.0.3.0 - 64bit Production on星期二, 25 8月, 2009 16:32:59

Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options
Starting "TEST"."SYS_EXPORT_TABLE_01": test/******** directory=d_output dumpfile=t_tt2.dp tables=(t,tt) content=metadata_only
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Master table "TEST"."SYS_EXPORT_TABLE_01" successfully loaded/unloaded
******************************************************************************
Dump file set for TEST.SYS_EXPORT_TABLE_01 is:
/home/oracle/t_tt2.dp
Job "TEST"."SYS_EXPORT_TABLE_01" successfully completed at 16:33:02

但是這種方法控制的是整體，現(xiàn)在需要對(duì)其中的個(gè)別對(duì)象只導(dǎo)出表結(jié)構(gòu)。最好想到的方法是通過(guò)QUERY來(lái)控制：

[oracle@yans1 ~]$ expdp test/test directory=d_output dumpfile=t_tt3.dp tables=(t,tt) query='t:"where 1=2"'

Export: Release 10.2.0.3.0 - 64bit Production on星期二, 25 8月, 2009 16:51:37

Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options
Starting "TEST"."SYS_EXPORT_TABLE_01": test/******** directory=d_output dumpfile=t_tt3.dp tables=(t,tt) query=t:"where 1=2"
Estimate in progress using BLOCKS method...
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 256 KB
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
. . exported "TEST"."T" 5.507 KB 0 rows
. . exported "TEST"."TT" 6.421 KB 72 rows
Master table "TEST"."SYS_EXPORT_TABLE_01" successfully loaded/unloaded
******************************************************************************
Dump file set for TEST.SYS_EXPORT_TABLE_01 is:
/home/oracle/t_tt.dp
Job "TEST"."SYS_EXPORT_TABLE_01" successfully completed at 16:51:41

通過(guò)對(duì)T表添加一個(gè)恒為FALSE的查詢條件，使得T表導(dǎo)出的時(shí)候獲取0條記錄，從而達(dá)到只導(dǎo)T的結(jié)構(gòu)的目的。

但是這種方法對(duì)于數(shù)據(jù)量比較大的表效率會(huì)比較低，因?yàn)镺racle會(huì)進(jìn)行導(dǎo)出的操作，只是在處理的時(shí)候?qū)⒂涗涍^(guò)濾掉，除了沒(méi)有將數(shù)據(jù)寫到導(dǎo)出文件，其他所有的操作都進(jìn)行了，因此效率很低。

而實(shí)際上，數(shù)據(jù)泵還有更好的辦法來(lái)解決這個(gè)問(wèn)題：使用EXCLUDE參數(shù)。

[oracle@yans1 ~]$ expdp test/test directory=d_output dumpfile=t_tt4.dp tables=(t,tt) exclude=table/table_data:\"=\'T\'\"

Export: Release 10.2.0.3.0 - 64bit Production on星期二, 25 8月, 2009 16:59:39

Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options
Starting "TEST"."SYS_EXPORT_TABLE_01": test/******** directory=d_output dumpfile=t_tt4.dp tables=(t,tt) exclude=table/table_data:"='T'"
Estimate in progress using BLOCKS method...
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
Total estimation using BLOCKS method: 128 KB
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
. . exported "TEST"."TT" 6.421 KB 72 rows
Master table "TEST"."SYS_EXPORT_TABLE_01" successfully loaded/unloaded
******************************************************************************
Dump file set for TEST.SYS_EXPORT_TABLE_01 is:
/home/oracle/t_tt4.dp
Job "TEST"."SYS_EXPORT_TABLE_01" successfully completed at 16:59:43

這里看不到T表的信息，下面檢查一下導(dǎo)出是否生效：

[oracle@yans1 ~]$ sqlplus test/test

SQL*Plus: Release 10.2.0.3.0 - Production on星期二 8月 25 17:00:27 2009

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options

SQL> desc t
Name                                      Null?    Type
----------------------------------------- -------- ----------------------------
ID                                                 NUMBER
NAME                                      NOT NULL VARCHAR2(30)
TYPE                                               VARCHAR2(7)

SQL> drop table t;

Table dropped.

SQL> exit
Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options
[oracle@yans1 ~]$ impdp test/test directory=d_output dumpfile=t_tt4.dp tables=t

Import: Release 10.2.0.3.0 - 64bit Production on星期二, 25 8月, 2009 17:00:41

Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options
Master table "TEST"."SYS_IMPORT_TABLE_01" successfully loaded/unloaded
Starting "TEST"."SYS_IMPORT_TABLE_01": test/******** directory=d_output dumpfile=t_tt4.dp tables=t
Processing object type TABLE_EXPORT/TABLE/TABLE
Processing object type TABLE_EXPORT/TABLE/TABLE_DATA
Processing object type TABLE_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Job "TEST"."SYS_IMPORT_TABLE_01" successfully completed at 17:00:43

[oracle@yans1 ~]$ sqlplus test/test

SQL*Plus: Release 10.2.0.3.0 - Production on星期二 8月 25 17:00:47 2009

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options

SQL> select * from t;

no rows selected

很顯然，利用EXCLUDE的方式使得數(shù)據(jù)泵導(dǎo)出的時(shí)候去掉了T表的數(shù)據(jù)。

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