EXP的增量备份最小的差异单元是表，也就是说只要一个表的数据有变动，那么这个表就要被全表导出。
如果表的数据自上次备份以来没有任何变动，则该表将不会被再次导出。
实验数据库版本：
SQL> select * from v$version;
BANNER
——————————————————————————–
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 – 64bit Production
PL/SQL Release 11.2.0.4.0 – Production
CORE 11.2.0.4.0 Production
TNS for Linux: Version 11.2.0.4.0 – Production
NLSRTL Version 11.2.0.4.0 – Production
测试数据：
SQL> select * from test;
ID
———-
1
3
2
导出全库数据，其中test表数据3行：
[oracle@yfsl ~]$ exp test/test inctype=complete file=test-1.dmp
…
. about to export TEST’s tables via Conventional Path …
. . exporting table TEST 3 rows exported
. exporting synonyms
…
Export terminated successfully with warnings.
再次在表test中插入一条数据：
SQL> insert into test values(4);
1 row created.
SQL> commit;
Commit complete.
执行增量导出，导出test表结果为4行(此处验证只要表test中有一行数据变更，则会导出全表数据)：
[oracle@yfsl ~]$ exp test/test inctype=incremental file=test-2.dmp
…
. about to export SCOTT’s tables via Conventional Path …
. about to export TEST’s tables via Conventional Path …
. . exporting table TEST 4 rows exported
. exporting synonyms
. exporting views
…
Export terminated successfully with warnings.
对表test不做任何操作，再次增量导出，表test未重新导出数据(因为此时表test没有任何变更)：
[oracle@yfsl ~]$ exp test/test inctype=incremental file=test-3.dmp
…
. about to export OWBSYS_AUDIT’s tables via Conventional Path …
. about to export SCOTT’s tables via Conventional Path …
. about to export TEST’s tables via Conventional Path …
. exporting synonyms
. exporting views
…
Export terminated successfully with warnings.