SQL Server 2000 Indexed View with Max Subquery - sql

Question

I have a contracts table that is large and that we have many stored procedures that query for contracts with a status of Open. Less than 10% of the contracts are open and this number is shrinking as the DB grows. I thought I could create an Indexed view of the open contracts in order to speed up some of our queries. The problem is that the status is not on the contract table and I need a subquery to retrieve the data I want. (SQL Server then does a clustered index scan on the whole table in the queries I have looked at)
Here is the condensed version of the view (I removed the 30 other columns from the contract table)
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE VIEW [dbo].[vw_OpenContractsIndexed]
WITH SCHEMABINDING
AS
SELECT c.ContractID
FROM dbo.NMPT_Contract AS c INNER JOIN
dbo.NMPT_ContractStatus AS cs ON c.ContractID = cs.ContractID AND cs.ContractStatusCreated =
(SELECT MAX(ContractStatusCreated) AS Expr1
FROM dbo.NMPT_ContractStatus AS cs2
WHERE (ContractID = c.ContractID)) INNER JOIN
dbo.CMSS_Status AS s ON cs.StatusID = s.StatusID
WHERE (s.StatusCode = 'OPN')
If I try to create an index on the view (unique clustered on contractid) I get the following
Creation Failed for Index
It contains one or more disallowed constructs. (Microsoft SQL Server, Error 1936)
From what I can gather it is the Max in the subquery that is the problem??
Other than putting the status on the contracts table (where I personally think it belongs) are there any suggestions for optimising this situation. Failing that will other versions of SQL Server allow this indexed view?

Answer 1

From TechNet regarding Indexed Views in SS 2000:
There are several restrictions on the syntax of the view definition.
The view definition must not contain the following:
COUNT(*)
ROWSET function
Derived table
self-join
DISTINCT
STDEV, VARIANCE, AVG
Float*, text, ntext, image columns
Subquery
full-text predicates (CONTAIN, FREETEXT)
SUM on nullable expression
MIN, MAX
TOP
OUTER join
UNION
You're using MAX, and a subquery, both of which are not allowed.
To get advice on how to get around this, you need to share some data and what you are trying to do.

Answer 2

It is not a "View" solution and will require more work to accomplish, but you can create denormalized table which will hold the result of the view. This way, all reads for Open contracts can go against that table. This will be the fastest, but will require maintenance of the new table.

Answer 3

Creating an indexed view is quiet difficuylt task as it has so many restirction and one is related to self join as well. You have self join here.No other views etc.
Other thing for these kind of master tables if you are using just a single status like 'OPEN' in you case I would suggest that instead of joining the table (master table with status code) just declare statusid variable and then store the value for status OPEN there and then use that value in final query. This will avoid extra join with a master table.
I would suggest that you store the data for open status in temp table before joining with contract table in final statement. You can have an index on statusid,customerid and contractcreationdate. Then force this index to get the contractId into a temp table like
select contractid into #temp from NMPT_ContractStatus
where statusid =#statusid group by contractid
having datefield = max(datefield)
Now join this temp table with the Contract table.
But before creating any kind of indexes make sure that the overhead of these are much less than the benefits you are getting.