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【赛迪网－it技术报道】在实际的工作环境下，如果你在操作时将数据库内的几个数据字典表truncate掉，将会直接导致数据库不能再继续使用，本文将针对一个相关案例进行详细的讲解。
案例如下：
数据库环境：oracle数据库9.2.0.7 rac。（注：由于数据库的事务量体别大，所以数据库没有进行备份）。
检查后发现的被截断表：
sql> select object_name,object_type from dba_objects where object_name like 'idl%';
object_name object_type
------------------- ------------------
idl_char$ table
idl_sb4$ table
idl_ub1$ table
idl_ub2$ table
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idl_ub1$表是特别重要的字典表，只要出现故障，数据库就会出现大量的ora-00600错误，所有事务将不能进行。
ora-00600: internal error code, arguments: [17069],
[0xc0000000dddfa690], [], [], [], [], [], []
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ora-600 17069错误是一个特别难解决的问题，问题出现后数据库的某个跟踪日志很快就会出现暴涨的情况，因为idl系列字典表是记录数据库对象编译信息的，丢失了其中的数据，所有过程、package等都将无法执行。
字典表作用的说明：
idl_ub1$ is one of four tables that hold compiled pl/sql code:
idl_ub1$
idl_char$
idl_ub2$
idl_sb4$
"pl/sql is based on the programming language ada. as a result, pl/sql uses a
variant of descriptive intermediate attributed notation for ada (diana), which
is a tree-structured intermediate language. it is defined using a meta-notation
called interface definition language (idl). diana provides for communication
internal to compilers and other tools.
"at compile time, pl/sql source code is translated into machine-readable
m-code.both the diana and m-code for a procedure or package are stored in the
database.at run time, they are loaded into the shared (memory) pool. the diana is
used to compile dependent procedures; the m-code is simply executed."
these four tables hold the diana and the so-code m-code. i think "m-code" is
short for machine-dependent byte code but there is a sizable machine-indenpendent part
as well. if you have a look at sql.bsq, you can see
that oracle documents the "type" column of these tables as follows:
part number not null,
/* part: 0 = diana, 1 = portable pcode,
2 = machine-dependentpcode */
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如果出现更为严重的情况，它将导致大量系统dbms包失效，其重新编译也将更为复杂。
恢复数据库，消除所有ora-600错误的方法：
恢复的方法是通过运行相关的脚本，重建和重新编译所有procedure/trigger/package等对象，重新生成这些对象的diana和so-code m-code，主要包括catlog.sql,catproc.sql等脚本。
注意：即使以花费大量的时间为代价，一些ora-00600错误也必须解决。
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