优化慢更新查询

Question

I have two tables:

1) Testone - has 100k rows and 1 Index and 6 NON-Clustered index

2) Testtwo - has 316 Million rows, 1 Index and 4 NON-Clustered index

I have update statement need to optimize the following one due to taking more time when executing this query, could you please help me the best approach..

update mp 
set mp.ModelInfoID = mi.ModelInfoID 
from Testone mp 
inner join Testtwo mi on mp.ModelNumberStr = replace(replace(mi.Model, '/', ''), '-', '') 
where MemberID is not null and mp.ModelInfoID is null

Answer 1

start with just optimizing this
look at the query plan
index on MemberID, mp.ModelInfoID, and mi.ModelInfoID will help

select mp.ModelInfoID, mi.ModelInfoID 
  from Testone mp 
  join Testtwo mi 
    on mp.ModelNumberStr = replace(replace(mi.Model, '/', ''), '-', '') 
   and MemberID is not null 
   and mp.ModelInfoID is null
   and mi.ModelInfoID is not null -- no need to update if they are the same

Cleary the replace(replace(mi.Model, '/', ''), '-', '') is going to be the bottle neck. A computed column with an index may do the trick.