When you table get a changes a lot your table index might get fragment, so u can use the below query to find the fragmented index.

Fragment-Index.sql

select
  'exec analyzedb.reorg_a_table4('||' '||rtrim(t.table_owner)|| ' ' ||','|| ' ' ||
rtrim(t.table_name)||' '||');',
  t.table_owner||'.'||t.table_name name,
  a.num_rows,
  sum(t.inserts) ins,
  sum(t.updates) upd,
  sum(t.deletes) del,
  sum(t.updates)+sum(t.inserts)+sum(t.deletes) tot_chgs,
  to_char((sum(t.deletes)/(decode(a.num_rows,0,1,a.num_rows)))*100.0,'999999.99') per_del,
  round(((sum(t.updates)+sum(t.inserts)+sum(t.deletes))/(decode(a.num_rows,0,1,a.num_rows)) *100.0),2) per_chg
from DBA_TAB_MODIFICATIONS t, all_tables a
where t.timestamp >= to_date(sysdate - 200,'dd-mon-yyyy')
  and t.table_owner = a.owner and t.table_owner not in ('SYS','SYSTEM')
  and t.table_name=a.table_name
  and t.table_name = 'GSM_SERVICE_MAST'
group by t.table_owner, t.table_name, a.num_rows
--having (sum(t.deletes)/(decode(a.num_rows,0,1,a.num_rows)))*100.0 >=5
order by num_rows desc, t.table_owner, t.table_name;