Sql query slowness due to rank and columns with null values:

Question

    
Sql query slowness due to rank and columns with null values:
I have the following table in database with around 10 millions records:
Declaration:
create table PropertyOwners (
[Key] int not null primary key,
PropertyKey int not null,    
BoughtDate DateTime,    
OwnerKey int null,    
GroupKey int null   
go
[Key] is primary key and combination of PropertyKey, BoughtDate, OwnerKey and GroupKey is unique.
With the following index:
CREATE NONCLUSTERED INDEX [IX_PropertyOwners] ON [dbo].[PropertyOwners]    
[PropertyKey] ASC,   
[BoughtDate] DESC,   
[OwnerKey] DESC,   
[GroupKey] DESC   
go
Description of the case:
For single BoughtDate one property can belong to multiple owners or single group, for single record there can either be OwnerKey or GroupKey but not both so one of them will be null for each record. I am trying to retrieve the data from the table using
following query for the OwnerKey. If there are same property rows for owners and group at the same time than the rows having OwnerKey with be preferred, that is why I am using "OwnerKey desc" in Rank function.
declare @ownerKey int = 40000   
select PropertyKey, BoughtDate, OwnerKey, GroupKey   
from (    
select PropertyKey, BoughtDate, OwnerKey, GroupKey,       
RANK() over (partition by PropertyKey order by BoughtDate desc, OwnerKey desc, GroupKey desc) as [Rank]   
from PropertyOwners   
) as result   
where result.[Rank]=1 and result.[OwnerKey]=@ownerKey
It is taking 2-3 seconds to get the records which is too slow, similar time it is taking as I try to get the records using the GroupKey. But when I tried to get the records for the PropertyKey with the same query, it is executing in 10 milliseconds.
May be the slowness is due to as OwnerKey/GroupKey in the table  can be null and sql server in unable to index it. I have also tried to use the Indexed view to pre ranked them but I can't use it in my query as Rank function is not supported in indexed
view.
Please note this table is updated once a day and using Sql Server 2008 R2. Any help will be greatly appreciated.

Answer 1

create table #result (PropertyKey int not null, BoughtDate datetime, OwnerKey int null, GroupKey int null, [Rank] int not null)Create index idx ON #result(OwnerKey ,rnk)
insert into #result(PropertyKey, BoughtDate, OwnerKey, GroupKey, [Rank])
select PropertyKey, BoughtDate, OwnerKey, GroupKey,
RANK() over (partition by PropertyKey order by BoughtDate desc, OwnerKey desc, GroupKey desc) as [Rank]
from PropertyOwners
go
declare @ownerKey int = 1
select PropertyKey, BoughtDate, OwnerKey, GroupKey
from #result as result
where result.[Rank]=1
and result.[OwnerKey]=@ownerKey
go
Best Regards,Uri Dimant SQL Server MVP,
http://sqlblog.com/blogs/uri_dimant/
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