关于SQL优化的一个小试例子

原SQL：

select ta.serialno,
ta.accepttime,
ta.subsnumber,
ta.subsname,
ta.contactphone1,
ta.servicecontent,
ta.address,
r.region_name,
s.contactchannel_name,
p.name,
p.fullname,
rownum
from (select t.serialno,
t.accepttime,
t.subsnumber,
t.subsname,
t.contactphone1,
t.servicecontent,
t.address,
t.contactchannel,
t.srtypeid,
t.partition_id_region
FROM report_threed_problemprocess t,
(select trim(t1.para) p1
FROM System_Parameters_t t1
WHERE t1.para_flag = 'OVER_GONGXINBYCL_TYPE') a,
(SELECT trim(t2.para) p2
FROM System_Parameters_t t2
WHERE t2.para_flag = 'OVER_GONGXINBYCL_CHANNEL') b,
(SELECT TRIM(t3.para) p3
FROM System_Parameters_t t3
WHERE t3.para_flag = 'OVER_96180_TYPE') c
WHERE t.partition_id_month = uf_get_partition_month(201306)
and t.accepttime>=to_date(201306||'01','yyyymmdd') and t.accepttime<add_months(to_date(201306||'01','yyyymmdd'),1)
and t.partition_id_region in
(SELECT rt.ioid_id0 region_id
FROM region_t rt
WHERE rt.region_level = 4
AND rt.ioid_id0 >= 1001
AND rt.ioid_id0 <= 1018)
AND t.srtypeid IN (SELECT spp.srtype_id
FROM sdt_para_pro_com_tsnote spp
WHERE spp.pro_com_id =1025
AND state = 1)
AND ((substr(t.srtypeid, 1, 6) = a.p1 and t.contactchannel = b.p2) or
(substr(t.srtypeid, 1, 6) = c.p3 and t.contactchannel = b.p2))
) ta --96180
inner join sdt_para_contactchannel s
on ta.contactchannel = s.contactchannel
inner join sdt_servicerequesttype p
on ta.srtypeid = p.srtypeid
inner join region_t r
on r.ioid_id0=ta.partition_id_region;

在数据库上的执行时间为：65.969s

改进后的SQL：

select ta.serialno,
ta.accepttime,
ta.subsnumber,
ta.subsname,
ta.contactphone1,
ta.servicecontent,
ta.address,
(SELECT r.region_name FROM region_t r WHERE r.ioid_id0=ta.partition_id_region)region_name,
(SELECT s.contactchannel_name FROM sdt_para_contactchannel s WHERE ta.contactchannel = s.contactchannel) contactchannel_name,
p.name,
p.fullname,
rownum
from (select t.serialno,
t.accepttime,
t.subsnumber,
t.subsname,
t.contactphone1,
t.servicecontent,
t.address,
t.contactchannel,
t.srtypeid,
t.partition_id_region
FROM report_threed_problemprocess t
WHERE t.partition_id_month = uf_get_partition_month(201306)
and t.accepttime>=to_date(201306||'01','yyyymmdd') and t.accepttime<add_months(to_date(201306||'01','yyyymmdd'),1)
AND t.srtypeid IN (SELECT spp.srtype_id FROM sdt_para_pro_com_tsnote spp
WHERE spp.pro_com_id =1025 AND state = 1)
AND
(
(substr(t.srtypeid, 1, 6) =(select trim(t1.para) FROM System_Parameters_t t1 WHERE t1.para_flag = 'OVER_GONGXINBYCL_TYPE')
and t.contactchannel =(SELECT trim(t2.para) p2 FROM System_Parameters_t t2 WHERE t2.para_flag = 'OVER_GONGXINBYCL_CHANNEL')
)
or
(substr(t.srtypeid, 1, 6) =(SELECT TRIM(t3.para) p3 FROM System_Parameters_t t3 WHERE t3.para_flag = 'OVER_96180_TYPE')
and t.contactchannel =(SELECT trim(t2.para) p2 FROM System_Parameters_t t2 WHERE t2.para_flag = 'OVER_GONGXINBYCL_CHANNEL')
)
)
) ta --96180
inner join sdt_servicerequesttype p
on ta.srtypeid = p.srtypeid;
执行时长：9.17s

暂时记这么多。