1. 表占用空间大小计算方法 select s.segment_name ,decode(sum(bytes), null, 0, sum(bytes) / 1024 / 1024) mbytes from
1.       表占用空间大小计算方法
select s.segment_name ,decode(sum(bytes), null, 0, sum(bytes) / 1024 / 1024) mbytes
from dba_segments s
where s.segment_name = 'mtl_material_transactions' --表名
and s.segment_type = 'table'
group by s.segment_name
2.       索引占用空间大小计算方法
select s.segment_name ,decode(sum(bytes), null, 0, sum(bytes) / 1024 / 1024) mbytes
from dba_segments s
where s.segment_name = 'mtl_material_transactions_n1' --索引
and s.segment_type = 'index'
group by s.segment_name
3.       分区表占用空间大小计算方法
select s.segment_name ,decode(sum(bytes), null, 0, sum(bytes) / 1024 / 1024) mbytes
from dba_segments s
where s.segment_type = 'table partition'
group by s.segment_name
4.       表空间使用情况
select a.tablespace_name 表空间名称,
round(a.bytes, 2) 总空间(g),
round(b.bytes, 2) 未用空间(g),
round(((a.bytes - b.bytes) / a.bytes) * 100, 2) 使用率%
from (select tablespace_name, sum(bytes) / (1024 * 1024 * 1024) bytes
from dba_data_files
group by tablespace_name) a,
(select tablespace_name, sum(bytes) / (1024 * 1024 * 1024) bytes
from dba_free_space
group by tablespace_name) b
where a.tablespace_name = b.tablespace_name
order by ((a.bytes - b.bytes) / a.bytes) desc;
，