?
Solved

indexed views not being used by optimizer

Posted on 2011-09-08
3
Medium Priority
?
341 Views
Last Modified: 2012-05-12
Please run the code below in a scratch database.  On the last query, check the execution plan.  Why does it do a full table scan instead of doing an index seek on the covering index of the view?

The goal is to do a case-insensitive search on the LastName column, which in my real base table is collation Latin1_General_BIN (the server default here), by way of an index seek, not a scan.  I thought I could do this by creating a view of the table and setting the collation on that field to SQL_Latin1_General_CP1_CI_AS in the view, and index this version of the column on the view.

Thanks
create table dbo.tTest(id int identity(1,1), LastName varchar(80) COLLATE Latin1_General_BIN, FirstName varchar(80) COLLATE Latin1_General_BIN) 
GO

create unique clustered index tx0 on dbo.tTest(id)
GO

insert into dbo.tTest select 'Doe','John'
insert into dbo.tTest select 'Doe','Jane'
insert into dbo.tTest select 'Bach','Hellen'
insert into dbo.tTest select 'Smith','Jane'
insert into dbo.tTest select 'Smith','Mike'
insert into dbo.tTest select 'Jones','Mike'
GO

create view dbo.vTest  WITH SCHEMABINDING  as
select id, (LastName COLLATE SQL_Latin1_General_CP1_CI_AS) as LastName, (FirstName COLLATE SQL_Latin1_General_CP1_CI_AS) as FirstName
from dbo.tTest
GO

create unique clustered index vx0 on dbo.vTest(id) 
GO

create unique index vx1 on dbo.vTest(LastName,FirstName,id)
GO

select id, FirstName, LastName
from dbo.vTest -- with (index=vx1)
where LastName  = 'BACH'  
GO

--  drop view dbo.vTest
--  truncate table dbo.tTest
--  drop table dbo.tTest
GO

Open in new window

0
Comment
Question by:knightEknight
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
3 Comments
 
LVL 33

Author Comment

by:knightEknight
ID: 36505422
FYI - I can achieve the overall goal by creating calculated fields on the base table instead of a view (see below), but I would rather get this to work in a view:
use staging
GO

create table dbo.tTest(
                        id int identity(1,1), 
                        LastName  varchar(80) COLLATE Latin1_General_BIN, 
                        FirstName varchar(80) COLLATE Latin1_General_BIN,
                        cLastName  as (LastName  COLLATE SQL_Latin1_General_CP1_CI_AS),
                        cFirstName as (FirstName COLLATE SQL_Latin1_General_CP1_CI_AS)
                      ) 
GO

create unique clustered index tx0 on dbo.tTest(id)
GO

insert into dbo.tTest select 'Doe','John'
insert into dbo.tTest select 'Doe','Jane'
insert into dbo.tTest select 'Bach','Hellen'
insert into dbo.tTest select 'Smith','Jane'
insert into dbo.tTest select 'Smith','Mike'
insert into dbo.tTest select 'Jones','Mike'
GO

create unique index tx1 on dbo.tTest(cLastName,cFirstName,id)
GO

select id, cFirstName, cLastName
from dbo.tTest
where cLastName  = 'BACH'

--  drop view dbo.vTest
--  truncate table dbo.tTest
--  drop table dbo.tTest

Open in new window

0
 
LVL 33

Accepted Solution

by:
knightEknight earned 0 total points
ID: 36505439
I need to revise my overall goal here:

The goal is to do a case-insensitive search on the LastName column by way of an index seek, not a scan, which in my real base table is collation Latin1_General_BIN (the server default here).
0
 
LVL 33

Author Closing Comment

by:knightEknight
ID: 36506136
starting over ...
0

Featured Post

Microsoft Certification Exam 74-409

Veeam® is happy to provide the Microsoft community with a study guide prepared by MVP and MCT, Orin Thomas. This guide will take you through each of the exam objectives, helping you to prepare for and pass the examination.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Long way back, we had to take help from third party tools in order to encrypt and decrypt data.  Gradually Microsoft understood the need for this feature and started to implement it by building functionality into SQL Server. Finally, with SQL 2008, …
This article explains how to reset the password of the sa account on a Microsoft SQL Server.  The steps in this article work in SQL 2005, 2008, 2008 R2, 2012, 2014 and 2016.
This tutorial will teach you the special effect of super speed similar to the fictional character Wally West aka "The Flash" After Shake : http://www.videocopilot.net/presets/after_shake/ All lightning effects with instructions : http://www.mediaf…
Visualize your data even better in Access queries. Given a date and a value, this lesson shows how to compare that value with the previous value, calculate the difference, and display a circle if the value is the same, an up triangle if it increased…

741 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question