Query too slow! Need some performance enhancing tips!

I have a stored procedure that queries a database using a Select
statement with some inner joins and conditions. With over 9 million
records it takes 1 min 36 sec to complete. This is too slow for my
requirements.

Is there any way I can optimize this query. I have thought about
using an indexed view. I haven't done one before, does anyone know if
this would have potential to improve performance or indeed any other
performance enhancing techniques I might try.

SELECT vehicle.vehicle_id
FROM (( [vehicle]
INNER JOIN [vehicle_subj_item_assn] on
vehicle.vehicle_id=[vehicle_subj_item_assn].vehicle_id)
INNER JOIN [subj_item] on
[vehicle_subj_item_assn].subj_item_id=[subj_item].subj_item_id)
INNER JOIN [template_field] on
[subj_item].subj_item_id=[template_field].subj_attr_id
WHERE
([template_field].template_field_id=@.template_field_id) AND
([template_field].template_field_type_id=3) AND
([vehicle_subj_item_assn].subj_item_value_text=@.value) AND
(vehicle.end_dtm IS NOT NULL)

Thanks
GavinOn 1 Dec 2004 06:17:40 -0800, gizmo@.consultant.com wrote:

>I have a stored procedure that queries a database using a Select
>statement with some inner joins and conditions. With over 9 million
>records it takes 1 min 36 sec to complete. This is too slow for my
>requirements.
>Is there any way I can optimize this query. I have thought about
>using an indexed view. I haven't done one before, does anyone know if
>this would have potential to improve performance or indeed any other
>performance enhancing techniques I might try.
>SELECT vehicle.vehicle_id
>FROM (( [vehicle]
>INNER JOIN [vehicle_subj_item_assn] on
>vehicle.vehicle_id=[vehicle_subj_item_assn].vehicle_id)
>INNER JOIN [subj_item] on
>[vehicle_subj_item_assn].subj_item_id=[subj_item].subj_item_id)
>INNER JOIN [template_field] on
>[subj_item].subj_item_id=[template_field].subj_attr_id
>WHERE
>([template_field].template_field_id=@.template_field_id) AND
>([template_field].template_field_type_id=3) AND
>([vehicle_subj_item_assn].subj_item_value_text=@.value) AND
>(vehicle.end_dtm IS NOT NULL)
>Thanks
>Gavin

Hi Gavin,

I don't think you need all those paretheses and brackets. They don't hurt
performance, but they do make the query harder to read.

Also, you never use any column in subj_item. I think you can remove that
table (unless it is ppossible that some value of subj_item_id that does
not exist in subj_item does exist in vehicle_subj_item_assn.subj_item_id
and template_field.subj_attr_id). I don't see any way to improve on the
remaining query:

SELECT vehicle.vehicle_id
FROM vehicle
INNER JOIN vehicle_subj_item_assn
ON vehicle.vehicle_id = vehicle_subj_item_assn.vehicle_id
INNER JOIN template_field
ON vehicle_subj_item_assn.subj_item_id=template_field .subj_attr_id
WHERE template_field.template_field_id = @.template_field_id
AND template_field.template_field_type_id = 3
AND vehicle_subj_item_assn.subj_item_value_text = @.value
AND vehicle.end_dtm IS NOT NULL
(untested)

An other way to optimize this is to look at your indexes. I don't think an
indexed view will do you much good (though you can always try, of course -
remember to test a typical workload, as this specific information will
return faster, but update performance will suffer) - indexed views are
often used for views with aggregations.

Best, Hugo
--

(Remove _NO_ and _SPAM_ to get my e-mail address)|||(gizmo@.consultant.com) writes:
> I have a stored procedure that queries a database using a Select
> statement with some inner joins and conditions. With over 9 million
> records it takes 1 min 36 sec to complete. This is too slow for my
> requirements.
> Is there any way I can optimize this query. I have thought about
> using an indexed view. I haven't done one before, does anyone know if
> this would have potential to improve performance or indeed any other
> performance enhancing techniques I might try.

You could materialize the query into an indexed view, but I would suspect
that it is an overkill.

You can probably improve performance considerably by reviewing indexes.
96 seconds for 9 millions rows sounds like a table is being scanned
somewhere. However, I cannot do that for you, since you have not submitted
enough with information.

I would suggest that you post the CREATE TABLE and CREATE INDEX statments
for your tables, as well as the approxamite rowcount for the tables.

Also consider Hugo's note about the subj_item table. It may not fill a
function in the query. (Then again, it could serve as an EXISTS condition.)
--
Erland Sommarskog, SQL Server MVP, esquel@.sommarskog.se

Books Online for SQL Server SP3 at
http://www.microsoft.com/sql/techin.../2000/books.asp|||Have you checked out http://www.xprime.com

We've been using their database accelerator for MS SQL with good
results... 5X on many of our stored procs, similar to those you
describe below.

Tony

gizmo@.consultant.com wrote:
> I have a stored procedure that queries a database using a Select
> statement with some inner joins and conditions. With over 9 million
> records it takes 1 min 36 sec to complete. This is too slow for my
> requirements.
> Is there any way I can optimize this query. I have thought about
> using an indexed view. I haven't done one before, does anyone know
if
> this would have potential to improve performance or indeed any other
> performance enhancing techniques I might try.
> SELECT vehicle.vehicle_id
> FROM (( [vehicle]
> INNER JOIN [vehicle_subj_item_assn] on
> vehicle.vehicle_id=[vehicle_subj_item_assn].vehicle_id)
> INNER JOIN [subj_item] on
> [vehicle_subj_item_assn].subj_item_id=[subj_item].subj_item_id)
> INNER JOIN [template_field] on
> [subj_item].subj_item_id=[template_field].subj_attr_id
> WHERE
> ([template_field].template_field_id=@.template_field_id) AND
> ([template_field].template_field_type_id=3) AND
> ([vehicle_subj_item_assn].subj_item_value_text=@.value) AND
> (vehicle.end_dtm IS NOT NULL)
> Thanks
> Gavin