谁能帮我优化一下这个oracle的sql语句？

Question

sql语句如下：
select zonecode as zonecode,
       nvl(t.chargesrc, '-1') as chargesrc ,
       nvl(t.infectapp, '-1') as infectapp,
       sum(t.counts) as counts,
       sum(case
             when t.flwcount = 1 then
              1
             else
              0
           end) as sumflw1, --完成一次随访
       sum(case
             when t.flwcount = 2 then
              1
             else
              0
           end) as sumflw2, --完成两次随访
       sum(case
             when t.flwcount = 2 then
              1
             else
              0
           end) as sumflw3, --完成三次随访
       sum(case
             when t.flwcount = 2 then
              1
             else
              0
           end) as sumflw4, --完成四次随访
       sum(case
             when t.cd4count = 1 then
              1
             else
              0
           end) as cd41, --完成一次cd4检测
       sum(case
             when t.cd4count = 2 then
              1
             else
              0
           end) as cd42, --完成两次cd4检测
       sum(case
             when t.virunlncount = 1 then
              1
             else
              0
           end) as viruln1, --完成一次病毒载量
       sum(t.virunlnno) as noviruln ,--病毒载量被抑制 
       sum(t.initvirunlncount) as avirulnsum
  from (select a.card_id as card_id,
               a.zonecode as zonecode,
               a.chargesrc as chargesrc,
               a.infectapp as infectapp,
               sum(case
                     when a.dt_treatbegin <= to_date('2009-12-31', 'yyyy-mm-dd') and
                          a.tm_create <= to_date('2009-11-30', 'yyyy-mm-dd') then
                      1
                     else
                      0
                   end) as counts,
               0 as flwcount, -- 当年完成随访次数
               sum(case
                     when a.cd4 is not null and
                          a.dt_treatbegin <= to_date('2009-12-31', 'yyyy-mm-dd') and
                          a.tm_create <= to_date('2009-11-30', 'yyyy-mm-dd') then
                      1
                     else
                      0
                   end) as cd4count, --当年完成cd4检测数
               sum(case
                     when a.viruln is not null and
                          a.dt_treatbegin <= to_date('2009-12-31', 'yyyy-mm-dd') and
                          a.tm_create <= to_date('2009-11-30', 'yyyy-mm-dd') then
                      1
                     else
                      0
                   end) as virunlncount, --当年完成病毒载量
               0 as virunlnno,
                sum(case
                     when a.viruln is not null and
                          a.dt_treatbegin <= to_date('2009-12-31', 'yyyy-mm-dd') and
                          a.tm_create <= to_date('2009-11-30', 'yyyy-mm-dd') then
                      1
                     else
                      0
                   end) as initvirunlncount
          from aidszh_sgra_child_info a
         where not exists (select ''
                  from aidszh_sgra_child_flw m
                 where a.card_id = m.card_id) 
         group by a.card_id, a.zonecode, a.chargesrc, a.infectapp
        union all
        select b.card_id,
               b.zonecode as zonecode,
               b.chargesrc as chargesrc,
               b.infectapp as infectapp,
               sum(case
                     when b.dt_treatbegin <= to_date('2009-12-31', 'yyyy-mm-dd') and
                          c.tm_create <= to_date('2009-11-30', 'yyyy-mm-dd') and
                          c.is_flw = '1' and c.clinic_treatment != '4' and ( d.end_cause <>'1' and d.end_cause <>'2' and d.end_cause<>'4' or d.end_cause is null ) then
                      1
                     else
                      0
                   end) as counts,
               sum(case
                     when c.card_id is not null and
                          b.dt_treatbegin <= to_date('2009-12-31', 'yyyy-mm-dd') and
                          c.tm_create <= to_date('2009-11-30', 'yyyy-mm-dd') and
                          c.is_flw = '1' and c.clinic_treatment != '4' and ( d.end_cause <>'1' and d.end_cause <>'2' and d.end_cause<>'4' or d.end_cause is null ) then
                      1
                     else
                      0
                   end) as flwcount, --当年完成随访次数
               sum(case
                     when c.cd4 is not null and
                          b.dt_treatbegin <= to_date('2009-12-31', 'yyyy-mm-dd') and
                          c.tm_create <= to_date('2009-11-30', 'yyyy-mm-dd') and
                          c.is_flw = '1' and c.clinic_treatment != '4' and ( d.end_cause <>'1' and d.end_cause <>'2' and d.end_cause<>'4' or d.end_cause is null ) then
                      1
                     else
                      0
                   end) as cd4count, --完成cd4检测数
               sum(case
                     when c.viruln is not null and
                          b.dt_treatbegin <= to_date('2009-12-31', 'yyyy-mm-dd') and
                          c.tm_create <= to_date('2009-11-30', 'yyyy-mm-dd') and
                          c.is_flw = '1' and c.clinic_treatment != '4' and ( d.end_cause <>'1' and d.end_cause <>'2' and d.end_cause<>'4' or d.end_cause is null ) then
                      1
                     else
                      0
                   end) as virunlncount,
               sum(case
                     when b.viruln is not null and b.viruln <> '0' and
                          c.tm_create <= to_date('2009-11-30', 'yyyy-mm-dd') and
                          b.dt_treatbegin >= to_date('2009-01-01', 'yyyy-mm-dd') and
                          c.viruln = '0' and
                          (c.dt_flworinterp - b.dt_treatbegin >= 180) and
                          (c.dt_flworinterp - b.dt_treatbegin <= 360)
                          and  c.is_flw = '1' and c.clinic_treatment != '4' and ( d.end_cause <>'1' and d.end_cause <>'2' and d.end_cause<>'4' or d.end_cause is null ) then
                      1
                     else
                      0
                   end) as virunlnno, --病毒载量被抑制
                   sum(case
                     when b.viruln is not null and
                          b.dt_treatbegin >= to_date('2009-01-01', 'yyyy-mm-dd') and
                          c.tm_create <= to_date('2009-11-30', 'yyyy-mm-dd') and
                          c.is_flw = '1' and c.clinic_treatment != '3' and ( d.end_cause <>'1' and d.end_cause <>'2' and d.end_cause<>'4' or d.end_cause is null ) then
                      1
                     else
                      0
                   end) as initvirunlncount
          from aidszh_sgra_child_info b, aidszh_sgra_child_flw c,aidszh_sgra_child_newstatus d
         where b.card_id = c.card_id and d.card_id=b.card_id
         
         group by b.card_id, b.zonecode, b.chargesrc, b.infectapp) t
 group by zonecode,
       nvl(t.chargesrc, '-1'),
       nvl(t.infectapp, '-1')
其中，where语句条件列中都有索引。但是他没有走。下面看一下sql执行计划：执行效率太慢，怎么才能走的快些呢？？

Answer 1

不走索引有很多原因， 
1. 索引限制，不过楼主的SQL 没有看出来。 
2. 在表上做下统计在看看：
analyze table tablename compute statistics for all indexes;
3. optimizer_index_cost_adj 参数设置过大.该参数影响优化器选择索引还是全表扫描的倾向,建议将其设为40. 楼主可以在相应字段上用hint 强制走索引看看.比如：select /*+ index(table_name,index_name) */ a.card_id as card_id,       
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Answer 2

这个还要看你的select所占据的数据总量的大小啊！

Answer 3

系统认为用索引还不如全表扫描快，所以它就不用索引。
where语句条件列中都有索引,case语句里的呢？它们也是要计算的。
优化时建议在sqlplus用trace看看统计，不要光看执行计划。
set autotrace on
执行你的语句，看看统计结果。