某客户要做数据迁移，需要确认数据文件占用空间和数据实际使用空间

首先确认数据文件占用空间

JCQ0> select sum(bytes)/1024/1024/1024 from dba_data_files;

SUM(BYTES)/1024/1024/1024
-------------------------
               369.916992

大概约369GB

然后确认数据实际使用空间

JCQ0> select sum(bytes)/1024/1024/1024 from dba_segments;

SUM(BYTES)/1024/1024/1024
-------------------------
               22058279.8

额滴神啊，这是22058279.8GB，也就是22058TB，或者说22PB，顿时疯掉

不到400G的库，占用空间为22P，基本可以断定为数据字典损坏

经确认，相关的数据字典确实大的不靠谱

SEGMENT_NAME                                                                           BYTES
--------------------------------------------------------------------------------- ----------
APPLY$_CONF_HDLR_COLUMNS                                                          8.9335E+12
APPLY$_CONF_HDLR_COLUMNS_UNQ1                                                     8.9335E+12
APPLY$_CONF_HDLR_COLUMNS_UNQ2                                                     8.9335E+12
APPLY$_DEST_OBJ                                                                   8.9335E+12
APPLY$_DEST_OBJ_CMAP                                                              8.9335E+12
APPLY$_DEST_OBJ_OPS                                                               8.9335E+12
APPLY$_ERROR                                                                      8.9335E+12
APPLY$_ERROR_HANDLER                                                              8.9335E+12
APPLY$_ERROR_HANDLER_UNQ                                                          8.9335E+12
APPLY$_SOURCE_OBJ                                                                 8.9335E+12
APPLY$_SOURCE_SCHEMA                                                              8.9335E+12
......

对于数据字典的损坏可以通过重新运行catalog.sql和catproc.sql解决
而Oracle的解释是由于低端存储引起。

附：容量单位换算关系

D->N->Y->Z->E->P->T->G->M->K->B

(需要引用, 请注明出处:痴情甲骨文http://space.itpub.net/14130873)

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