select round((1-a.used/b.num_total)*100,0) percent from
(SELECT COUNT (DISTINCT SUBSTR(rowid,1,15)) Used FROM 表名) a,
(select blocks num_total from dba_tables where table_name='表名' and wner='用户名') b;


通过dba_tables里的blocks字段和有数据的字段做对比，在用1减，求出没有数据的块的百分比（一般超过20%就需要回收了）从而判定是否需要回收高水位线


SQL> alter table test_shrik enable row movement ;
SQL> alter table test_shrik shrink space ;
SQL> select t.table_name,BLOCKS,EMPTY_BLOCKS,NUM_ROWS
from user_tables t
where table_name = upper('test_shrik');


exec dbms_stats.gather_table_stats('sys','test_shrik');


SQL> select t.table_name,BLOCKS,EMPTY_BLOCKS,NUM_ROWS
from user_tables t
where table_name = upper('test_shrik');


高水位线已经下降了