SQL：
select *
from (select distinct action_Type_Name as actionName,
toRZ,
custName,
partyTypeCd,
t.ol_nbr,
channelName,
staffName,
soDate,
ct.status,
ct.status as stName,
t.staff_number,
t.region_id,
t.region_name as areaName,
t.access_number,
'0' as wzType,
'' deal,
'' checkLog,
'' hzPdf,
'' cut,
'' olNbrLink,
pdf_type,
'' pdfZg,
case
when e.attr_value_name is null then
t.SYSTEM_SOURCE
else
e.attr_value_name
end system_source,
d.source_name as sourceName,
t.sd_staff as sdStaff,
t.sd_staff_name as sdStaffName
from YWJH.checkwz_scene t
left join YWJH.check_wz_zg_status ct
on t.ol_nbr = ct.ol_nbr
left join YWJH.checkwz_source d
on d.source_order = t.order_source
left join YWJH.sys_source_desc e
on e.attr_value = t.SYSTEM_SOURCE
where 1 = 1
AND (EXISTS (select 1
from YWJH.V_CHANNEL_BSS_staff_nj sto
where sto.staff_code = 'WTXF002'
and sto.org_id = t.channel_id) or
(t.sd_staff = 'WTXF002') or
(t.staff_number = 'WTXF002'))
and ct.status in ('F', 'RF', 'WC')
and t.city_id = '20'
union
select distinct action_Type_Name as actionName,
toRZ,
custName,
partyTypeCd,
t.ol_nbr,
channelName,
staffName,
soDate,
ct.status,
ct.status as stName,
t.staff_number,
t.region_id,
t.region_name as areaName,
t.access_number,
'1' as wzType,
'' deal,
'' checkLog,
'' hzPdf,
'' cut,
'' olNbrLink,
pdf_type,
'' pdfZg,
'' system_source,
'' sourceName,
'' sdStaff,
'' sdStaffName
from YWJH.checkwz_scene_wz_old t
left join YWJH.check_wz_zg_status ct
on t.ol_nbr = ct.ol_nbr
where 1 = 1
AND (EXISTS (select 1
from YWJH.V_CHANNEL_BSS_staff_nj sto
where sto.staff_code = 'WTXF002'
and sto.org_id = t.channel_id) or
(t.staff_number = 'WTXF002'))
and ct.status in ('F', 'RF', 'WC')
and t.city_id = '20'
) aa
order by aa.ol_nbr desc ;
執行計劃：
瞄了幾眼，這個SQL如果不該寫無法優化。
信不信由你，性能問題在 ID 14,20.
改寫後的SQL：
select *
from (select distinct action_Type_Name as actionName,
toRZ,
custName,
partyTypeCd,
t.ol_nbr,
channelName,
staffName,
soDate,
ct.status,
ct.status as stName,
t.staff_number,
t.region_id,
t.region_name as areaName,
t.access_number,
'0' as wzType,
'' deal,
'' checkLog,
'' hzPdf,
'' cut,
'' olNbrLink,
pdf_type,
'' pdfZg,
case
when e.attr_value_name is null then
t.SYSTEM_SOURCE
else
e.attr_value_name
end system_source,
d.source_name as sourceName,
t.sd_staff as sdStaff,
t.sd_staff_name as sdStaffName
from YWJH.checkwz_scene t
left join YWJH.check_wz_zg_status ct
on t.ol_nbr = ct.ol_nbr
left join YWJH.checkwz_source d
on d.source_order = t.order_source
left join YWJH.sys_source_desc e
on e.attr_value = t.SYSTEM_SOURCE
left join YWJH.V_CHANNEL_BSS_staff_nj sto on sto.staff_code = 'WTXF002' and sto.org_id = t.channel_id
where 1 = 1
and (sto.staff_id is not null or t.sd_staff = 'WTXF002'or t.staff_number = 'WTXF002')
and ct.status in ('F', 'RF', 'WC')
and t.city_id = '20'
union
select distinct action_Type_Name as actionName,
toRZ,
custName,
partyTypeCd,
t.ol_nbr,
channelName,
staffName,
soDate,
ct.status,
ct.status as stName,
t.staff_number,
t.region_id,
t.region_name as areaName,
t.access_number,
'1' as wzType,
'' deal,
'' checkLog,
'' hzPdf,
'' cut,
'' olNbrLink,
pdf_type,
'' pdfZg,
'' system_source,
'' sourceName,
'' sdStaff,
'' sdStaffName
from YWJH.checkwz_scene_wz_old t
left join YWJH.check_wz_zg_status ct on t.ol_nbr = ct.ol_nbr
left join YWJH.V_CHANNEL_BSS_staff_nj sto on sto.staff_code = 'WTXF002' and sto.org_id = t.channel_id
where 1 = 1
and ( sto.staff_id is not null or t.staff_number = 'WTXF002')
and ct.status in ('F', 'RF', 'WC')
and t.city_id = '20'
) aa
order by aa.ol_nbr desc ;
效率對比
優化前：125S， 2分鐘左右
優化後：13S
信不信由你，該SQL優化後， 業務高峯期業務量增加近2倍，CPU壓力減少 50%左右。
補一個後記吧。
本身該SQL優化不難， 只是對該項目有里程碑意義。 本身業務量就大，業務性能提升不上來， 需要整體優化，但並不是很難，本次優化基本上一眼定位到系統瓶頸。 之前寫博客紀念了一個SQl， 也是簡單看兩眼，從1997S優化到 0.2S。那次 個例上面看意義很大，這次對整體意義更大。 從接手優化這個系統，到定位到問題，再到解決問題。幾乎是很快的。所以這次也該紀念下。