查看碎片比：select tablespace_name,count(*) chunks,max(bytes/1024/1024) max_chunk from dba_free_space group by tablespace_name;
#CHUNK列表示表空间中可用有多少可用的空闲数据块，如果空闲块较多，超过100，则需要对相邻碎片进行整合
查看block_id极其不连续情况
select * from (SELECT segment_name,block_id ,LEAD( block_id) OVER ( ORDER BY block_id desc)/*整列向下移动一行*/ block_id_ FROM dba_extents) where block_id -block_id_ >10000