[20190324]奇怪的GV$FILESPACE_USAGE视图.txt

--//发现GV$FILESPACE_USAGE定义很奇怪,做一个记录.

1.环境:
SCOTT@book> @ ver1
PORT_STRING                    VERSION        BANNER
------------------------------ -------------- --------------------------------------------------------------------------------
x86_64/Linux 2.4.xx            11.2.0.4.0     Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

--//GV$FILESPACE_USAGE的定义如下:
SCOTT@book> select VIEW_NAME,VIEW_DEFINITION c100  from V$FIXED_VIEW_DEFINITION  where view_name='GV$FILESPACE_USAGE';
VIEW_NAME                      C100
------------------------------ ----------------------------------------------------------------------------------------------------
GV$FILESPACE_USAGE             SELECT inst_id, KTTEFINFOTSN, KTTEFINFOFNO, KTTEFINFOUSP,          KTTEFINFOSIZE, KTTEFINFOMSIZE, KT
                               TEFINFOSCNB,          KTTEFINFOSCNW, KTTEFINFOFLAG          FROM   X$KTTEFINFO
--//整理如下:
SELECT inst_id
      ,KTTEFINFOTSN
      ,KTTEFINFOFNO
      ,KTTEFINFOUSP
      ,KTTEFINFOSIZE
      ,KTTEFINFOMSIZE
      ,KTTEFINFOSCNB
      ,KTTEFINFOSCNW
      ,KTTEFINFOFLAG
  FROM X$KTTEFINFO;

2.增加数据文件:
ALTER TABLESPACE UNDOTBS1
  ADD DATAFILE '/mnt/ramdisk/book/undotbs02.dbf'
  SIZE 16M
  AUTOEXTEND OFF;

SCOTT@book> SELECT file#,ts#,rfile#,name,blocks,bytes FROM v$datafile;
FILE# TS# RFILE# NAME                             BLOCKS        BYTES
----- --- ------ -------------------------------- ------ ------------
    1   0      1 /mnt/ramdisk/book/system01.dbf    97280    796917760
    2   1      2 /mnt/ramdisk/book/sysaux01.dbf   120320    985661440
    3   2      3 /mnt/ramdisk/book/undotbs01.dbf  110720    907018240
    4   4      4 /mnt/ramdisk/book/users01.dbf