ORACLE常用SQL

oracle查看用户所占空间大小

SELECT owner, tablespace_name, ROUND (SUM (BYTES) / 1024 / 1024, 2) "USED(M)"

FROM dba_segments

GROUP BY owner, tablespace_name

ORDER BY SUM (BYTES) DESC;

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--1、查看表空间的名称及大小 

SELECT t.tablespace_name, round(SUM(bytes / (1024 * 1024)), 0) ts_size 

FROM dba_tablespaces t, dba_data_files d 

WHERE t.tablespace_name = d.tablespace_name 

GROUP BY t.tablespace_name; 

--2、查看表空间物理文件的名称及大小 

SELECT tablespace_name, 

file_id, 

file_name, 

round(bytes / (1024 * 1024), 0) total_space 

FROM dba_data_files 

ORDER BY tablespace_name; 

SELECT a.tablespace_name "表空间名",

total "表空间大小",

free "表空间剩余大小",

(total - free) "表空间使用大小",

total / (1024 * 1024 * 1024) "表空间大小(G)",

free / (1024 * 1024 * 1024) "表空间剩余大小(G)",

(total - free) / (1024 * 1024 * 1024) "表空间使用大小(G)",

round((total - free) / total, 4) * 100 "使用率 %"

FROM (SELECT tablespace_name, SUM(bytes) free

FROM dba_free_space

GROUP BY tablespace_name) a,

(SELECT tablespace_name, SUM(bytes) total

FROM dba_data_files

GROUP BY tablespace_name) b

WHERE a.tablespace_name = b.tablespace_name

--- 查看表空间建表语句

select dbms_metadata.get_ddl('TABLESPACE','HOS_DAT') from dual;

　11G中有个新特性，当表无数据时，不分配segment，以节省空间

Select segment_created,table_name from user_tables where segment_created = 'NO';