Oracle逻辑结构学习笔记

数据库(Database)由若干表空间(Tablespace)组成，表空间(Tablespace)由若干段(Segment)组成，段(Segment)由若干区(Extent)组成，区(Extent)又由若干块(Block)组成

查看表空间的总体情况：

SELECT A.TABLESPACE_NAME "表空间名",
A.TOTAL_SPACE "总空间(G)",
NVL(B.FREE_SPACE, 0) "剩余空间(G)",
A.TOTAL_SPACE - NVL(B.FREE_SPACE, 0) "使用空间(G)",
CASE
WHEN A.TOTAL_SPACE = 0 THEN
0
ELSE
trunc(NVL(B.FREE_SPACE, 0) / A.TOTAL_SPACE * 100, 2)
END "剩余百分比%" --避免分母为0
FROM (SELECT TABLESPACE_NAME,
trunc(SUM(BYTES) / 1024 / 1024 / 1024, 2) TOTAL_SPACE
FROM DBA_DATA_FILES
GROUP BY TABLESPACE_NAME) A,
(SELECT TABLESPACE_NAME,
trunc(SUM(BYTES / 1024 / 1024 / 1024), 2) FREE_SPACE
FROM DBA_FREE_SPACE
GROUP BY TABLESPACE_NAME) B
WHERE A.TABLESPACE_NAME = B.TABLESPACE_NAME(+)
ORDER BY 5;