How to change index scan to index seek in this case? - sql-server

Question

I have the following query on a sql server 2008 r2:
IF OBJECT_ID('tempdb..#temp') IS NOT NULL
/*Then it exists*/
DROP TABLE #temp
Select *
FROM
openquery(mysqlserver, 'select
id,street,name,customer,customerId
from table1 as t1
left join table2 as t2
on t2.id=t1.id
left join table3 as t3
on t3.id=t1.id
left join table4 as t4
on t4.id=t1.producto_id
left join table5 as t5
on t1.id = t5.id
where t1.type=0
and t3.service=''X''
and t1.check is null
and t1.date > date_sub(CURDATE(),INTERVAL 5 DAY)
')
SELECT * FROM #temp as t
left join View as v on v.customerId=t.customerId collate
SQL_Latin1_General_CP1_CI_AI
The above statement shows an execution plan where there is an index scan which costs 27% and another one which cost 26%. This is in related of the left join operation in one of the tables inside the view.
I thought to add index in the temp table with this:
CREATE NONCLUSTERED INDEX ix_temp_customerId on #temp(customerId)
It still the same, so I tried to apply the collate before to create the index:
ALTER TABLE #temp alter COLUMN customerId varchar(30) collate SQL_Latin1_General_CP1_CI_AI
Then the last query of the first statement was:
SELECT * FROM #temp as t
left join View as v on v.customerId=t.customerId
This shows the collation error despite the view uses this collation, and the tables inside the view query uses this collation. Then I add again the collate statement to the query.
The current statement is:
Select *
FROM
openquery(mysqlserver, 'select
id,street,name,customer,customerId
from table1 as t1
left join table2 as t2
on t2.id=t1.id
left join table3 as t3
on t3.id=t1.id
left join table4 as t4
on t4.id=t1.producto_id
left join table5 as t5
on t1.id = t5.id
where t1.type=0
and t3.service=''X''
and t1.check is null
and t1.date > date_sub(CURDATE(),INTERVAL 5 DAY)
')
ALTER TABLE #temp alter COLUMN customerId varchar(30) collate SQL_Latin1_General_CP1_CI_AI
CREATE NONCLUSTERED INDEX ix_temp_customerId on #temp(customerId)
SELECT * FROM #temp as t
left join View as v on v.customerId=t.customerId collate
SQL_Latin1_General_CP1_CI_AI
This execution plan still showing that there is an index scan. I would like to change this into index seek but I do not achieve that.
Any suggestion to achieve better performance?
Thank you

Answer 1

Share your execution plans using Paste The Plan # brentozar.com here are the instructions: How to Use Paste the Plan.
I would try explicitly creating your #temp table with the correct datatype, size, and collation (match the size of customerId to the varchar() size of View.customerId).
I would also consider including the columns in the index, since you are using select *.
create table #temp (
id int
, street varchar(128) collate SQL_Latin1_General_CP1_CI_AI
, name varchar(128) collate SQL_Latin1_General_CP1_CI_AI
, customer varchar(128) collate SQL_Latin1_General_CP1_CI_AI
, customerId varchar(30) collate SQL_Latin1_General_CP1_CI_AI
);
insert into #temp
select *
from openquery(mysqlserver, '
select
id,street,name,customer,customerId
from table1 as t1
left join table2 as t2
on t2.id=t1.id
left join table3 as t3
on t3.id=t1.id
left join table4 as t4
on t4.id=t1.producto_id
left join table5 as t5
on t1.id = t5.id
where t1.type=0
and t3.service=''X''
and t1.check is null
and t1.date > date_sub(CURDATE(),INTERVAL 5 DAY)
')
create nonclustered index ix_temp_customerId
on #temp(customerId)
include (id, street, name, customer);
select *
from #temp as t
left join View as v
on v.customerId=t.customerId