"Mansoor Azam" <mansoorb@shoa.net> wrote in message
news:c6l5ds$d8avq$1@ID-31123.news.uni-berlin.de...
> I have the following table with indexes
>
> CREATE TABLE dbo.Scratch (
>
> ItemID int IDENTITY (1, 1) NOT NULL ,
> Login varchar (12) NOT NULL ,
> StartDate datetime NULL ,
> PayDate datetime NULL ,
> LastDisconnect datetime NULL
>
> )
>
> GO
>
> CREATE INDEX idxPayDate ON dbo.Scratch(PayDate)
>
> GO
>
> CREATE INDEX idxStartDate ON dbo.Scratch(StartDate)
>
> GO
>
> The index distribution stats show a very poor average row hits (whatever
> that means) for these two indexes
>
> e.g for idxPaydate its 61160 (11.89% very poor )
>
> and there are many nulls in the distribution steps.
>
> Also I have many queries with conditions like (paydate is null and
startdate
> is not null etc) which means the index will not be used anyway (is this
> correct?). My application is giving timeouts for such queries.
>
> So my question is how can I make better indexes and make sure they are
used?
>
> thx
>
> (i'm using SQL 6.5 )
>
>
>
>

Mansoor Azam wrote:
>
> I have the following table with indexes
>
> CREATE TABLE dbo.Scratch (
>
> ItemID int IDENTITY (1, 1) NOT NULL ,
> Login varchar (12) NOT NULL ,
> StartDate datetime NULL ,
> PayDate datetime NULL ,
> LastDisconnect datetime NULL
>
> )
>
> GO
>
> CREATE INDEX idxPayDate ON dbo.Scratch(PayDate)
>
> GO
>
> CREATE INDEX idxStartDate ON dbo.Scratch(StartDate)
>
> GO
>
> The index distribution stats show a very poor average row hits (whatever
> that means) for these two indexes
>
> e.g for idxPaydate its 61160 (11.89% very poor )
>
> and there are many nulls in the distribution steps.
>
> Also I have many queries with conditions like (paydate is null and startdate
> is not null etc) which means the index will not be used anyway (is this
> correct?). My application is giving timeouts for such queries.
>
> So my question is how can I make better indexes and make sure they are used?
>
> thx
>
> (i'm using SQL 6.5 )