Timeout with SP. Would a composite index help (clustered or not)?
<p>Using SQL Server 2012. I have a table with over 10 million records.  Front end is a webform with multiple checkboxes, radiobuttons, two date textboxes (From/To), etc...</p>

<p>variables included in the WHERE statement of my stored procedure are:</p>

<ul>
<li>TIME_STAMP</li>
<li>STATE</li>
<li>JTYPE</li>
<li>CIE</li>
<li>newtech_ind</li>
<li>MD_SF_IND</li>
<li>FC_CD_IND</li>
<li>WL_IND</li>
<li>COMPLETED_IND</li>
<li>INTERV</li>
<li>DDINT</li>
<li>DAY_OF_WEEK</li>
</ul>

<p>Table is updated only once daily, early in the morning.  Traffic is low, it's intended for analysis purposes.</p>

<p>My current index is:</p>

<pre><code>CREATE CLUSTERED INDEX [IX_Summary] ON [dbo].[Summary]
(
    [TIME_STAMP] ASC,
    [STATE] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
GO
</code></pre>

<p>TIME_STAMP is used with the "From/To" textboxes.  It's the most important field as it is used by analysts to query different intervals, ranging from a single day, to many months at once.
Currently, I'm having timeouts when people select a wide interval range using that TIME_STAMP variable (which is datetime2(0) type).</p>

<p>I presume my index is at fault.  Would possibly adding a composite index which would include all the variables used in my WHERE clause help ?  Is there a better way ?</p>