1、查询现有表空间数据量；
-- system: 查询表空间使用情况
SELECT upper(f.tablespace_name) "Tablespace_name",
round((d.Tot_grootte_Mb - f.total_bytes) / d.Tot_grootte_Mb * 100,2) " Used (%) ",
round(f.total_bytes / d.Tot_grootte_Mb * 100,2) "Free (%)",
round(d.Tot_grootte_Mb/1024,2) "Total (GB)",
round((d.Tot_grootte_Mb - f.total_bytes)/1024,2) " Used (GB)",
round(f.total_bytes/1024,2) " Free_space (GB) "
FROM
(SELECT tablespace_name,
round(SUM(bytes)/(1024*1024),2) total_bytes,
round(MAX(bytes)/(1024*1024),2) max_bytes
FROM sys.dba_free_space
GROUP BY tablespace_name) f,
(SELECT dd.tablespace_name, round(SUM(dd.bytes)/(1024*1024),2) Tot_grootte_Mb
FROM sys.dba_data_files dd
GROUP BY dd.tablespace_name) d
WHERE d.tablespace_name = f.tablespace_name