LONG作为一种数据类型，在LOB大对象出现之后就不再推荐使用了。Oracle对LONG的态度是废弃，以至于一些新的工具对LONG类型的支持也并不好。
例如10g中推出的数据泵功能data pump expdp/impdp，在2个字符集完全一致(ZHS16GBK AL16UTF16)的数据库间导入、导出LONG 字段也可能存在乱码，这个现象在10g中比较常见。
对于该expdp/impdp long字段产生乱码的问题， Workaroud 的是用 exp/imp 传统导入导出工具来替代expdp /impdp，虽然export/import工具的速度不如data pump，但是因为是传统工具所以对于LONG这种近乎废弃的数据类型支持较好。
在11g上测试了一下，该乱码问题似乎已经得到修复：
SQL*Plus: Release 11.2.0.3.0 Production on 星期五 2月 22 06:13:53 2013 Copyright (c) 1982, 2011, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP, Data Mining and Real Application Testing options SQL> conn maclean/oracle Connected. SQL> SQL> SQL> SQL> SQL> create table tlong (t1 int, t2 long); Table created. SQL> insert into tlong values(1,'Maclean的测试'); 1 row created. SQL> commit; Commit complete. SQL> select t2 from tlong; T2 -------------------------------------------------------------------------------- Maclean的测试 1* select name,value$ from sys.props$ where name like '%CHARACTERSET%' SQL> / NAME VALUE$ ------------------------------ -------------------------------------------------- NLS_CHARACTERSET AL32UTF8 NLS_NCHAR_CHARACTERSET UTF8 [oracle@vmac1 ~]$ expdp maclean/oracle dumpfile=tmp:tlong.dmp tables=maclean.tlong Export: Release 11.2.0.3.0 - Production on 星期五 2月 22 06:18:55 2013 Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP, Data Mining and Real Application Testing options 启动 "MACLEAN"."SYS_EXPORT_TABLE_01": maclean/******** dumpfile=tmp:tlong.dmp tables=maclean.tlong 正在使用 BLOCKS 方法进行估计... 处理对象类型 TABLE_EXPORT/TABLE/TABLE_DATA 使用 BLOCKS 方法的总估计: 64 KB 处理对象类型 TABLE_EXPORT/TABLE/TABLE . . 导出了 "MACLEAN"."TLONG" 5.421 KB 1 行 已成功加载/卸载了主表 "MACLEAN"."SYS_EXPORT_TABLE_01" ****************************************************************************** MACLEAN.SYS_EXPORT_TABLE_01 的转储文件集为: /tmp/tlong.dmp 作业 "MACLEAN"."SYS_EXPORT_TABLE_01" 已于 06:19:14 成功完成 [oracle@vmac1 ~]$ impdp dumpfile=tmp:tlong.dmp remap_table=maclean.tlong:tlong1 Import: Release 11.2.0.3.0 - Production on 星期五 2月 22 06:21:34 2013 Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved. Username: maclean Password: Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP, Data Mining and Real Application Testing options 已成功加载/卸载了主表 "MACLEAN"."SYS_IMPORT_FULL_01" 启动 "MACLEAN"."SYS_IMPORT_FULL_01": maclean/******** dumpfile=tmp:tlong.dmp remap_table=maclean.tlong:tlong1 处理对象类型 TABLE_EXPORT/TABLE/TABLE 处理对象类型 TABLE_EXPORT/TABLE/TABLE_DATA . . 导入了 "MACLEAN"."TLONG1" 5.421 KB 1 行 作业 "MACLEAN"."SYS_IMPORT_FULL_01" 已于 06:21:39 成功完成 SQL> select * from tlong1; T1 ---------- T2 -------------------------------------------------------------------------------- 1 Maclean的测试
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