Query Tuning

Hi,
I have a query that selects 4 fields. One is of type Varchar(500). When I
execute the query, the response is about 9 seconds (very slow). When I
comment out the varchar field, it returns in less than 1 second.
It took me a while to figure out that it's not a missing index, i can't
figure this one out.
please advise.
rafaelHow many records are being returned?
"Rafael Chemtob" wrote:

> Hi,
> I have a query that selects 4 fields. One is of type Varchar(500). When
I
> execute the query, the response is about 9 seconds (very slow). When I
> comment out the varchar field, it returns in less than 1 second.
> It took me a while to figure out that it's not a missing index, i can't
> figure this one out.
> please advise.
> rafael
>
>|||10
"CBretana" <cbretana@.areteIndNOSPAM.com> wrote in message
news:6F062F1B-91A3-45B6-AB3E-F08DF4A37831@.microsoft.com...
> How many records are being returned?
> "Rafael Chemtob" wrote:
>
When I|||> How many records are being returned?
..And what is the average length of the data in those rows?
Thomas
"CBretana" <cbretana@.areteIndNOSPAM.com> wrote in message
news:6F062F1B-91A3-45B6-AB3E-F08DF4A37831@.microsoft.com...
> How many records are being returned?
> "Rafael Chemtob" wrote:
>|||ok, sorry for not being very detailed.
4 fields
id_rating INT
summary VARCHAR(500)
dt_rating smalldatetime
id_user INT
these are the 4 fields. The record count that's returned is 11 rows.
Hope that helps
thanks
"Thomas" <replyingroup@.anywhere.com> wrote in message
news:#45wbrTRFHA.2384@.tk2msftngp13.phx.gbl...
> ..And what is the average length of the data in those rows?
>
> Thomas
>
> "CBretana" <cbretana@.areteIndNOSPAM.com> wrote in message
> news:6F062F1B-91A3-45B6-AB3E-F08DF4A37831@.microsoft.com...
When I
>|||Is the performance discrepancy consistent? i.e., have you tested this a
number of times? How many records are in the table?,
and finally, is there an index on the table that contains all the other
three columns from the table, but not the varchar(500) column?
Also, please post the DDL for the tables, and the actual Query.
Charly
"Rafael Chemtob" wrote:

> ok, sorry for not being very detailed.
> 4 fields
> id_rating INT
> summary VARCHAR(500)
> dt_rating smalldatetime
> id_user INT
> these are the 4 fields. The record count that's returned is 11 rows.
> Hope that helps
> thanks
>
> "Thomas" <replyingroup@.anywhere.com> wrote in message
> news:#45wbrTRFHA.2384@.tk2msftngp13.phx.gbl...
> When I
>
>|||I mean, is there an index on the table which includes columns
(id_rating, dt_rating, id_user), but not Column summary ?
"Rafael Chemtob" wrote:

> ok, sorry for not being very detailed.
> 4 fields
> id_rating INT
> summary VARCHAR(500)
> dt_rating smalldatetime
> id_user INT
> these are the 4 fields. The record count that's returned is 11 rows.
> Hope that helps
> thanks
>
> "Thomas" <replyingroup@.anywhere.com> wrote in message
> news:#45wbrTRFHA.2384@.tk2msftngp13.phx.gbl...
> When I
>
>|||I query the table using id_rating (which is the PK).
and this is consistent. I comment out the varchar field and i get the
results MUCH quicker.
rafael
"CBretana" <cbretana@.areteIndNOSPAM.com> wrote in message
news:456CEB9F-6A05-464C-9EE5-93F4FF0B7DB3@.microsoft.com...
> I mean, is there an index on the table which includes columns
> (id_rating, dt_rating, id_user), but not Column summary ?
>
> "Rafael Chemtob" wrote:
>
When I
can't|||As I asked above, one possible reason for this is if there's an index that
includes the columns (id_rating, dt_rating, id_user), but NOT the summary
column. If that were the case, the query processor could use the index alon
e
for the query without Summary, but would be forced to do a table scan when
you include summary.. Is there such an index?
"Rafael Chemtob" wrote:

> I query the table using id_rating (which is the PK).
> and this is consistent. I comment out the varchar field and i get the
> results MUCH quicker.
> rafael
> "CBretana" <cbretana@.areteIndNOSPAM.com> wrote in message
> news:456CEB9F-6A05-464C-9EE5-93F4FF0B7DB3@.microsoft.com...
> When I
> can't
>
>|||Hi Rafael,
For performance questions like these, it is very important to post all
relevant DDL (so including indexes, constraints, etc.) and the exact
query.
So just a wild guess for now: make sure you have a clustered index on
the table. If the table does not have a clustered index, and you delete
many rows, then querying the table can become very slow.
HTH,
Gert-Jan
Rafael Chemtob wrote:
> Hi,
> I have a query that selects 4 fields. One is of type Varchar(500). When
I
> execute the query, the response is about 9 seconds (very slow). When I
> comment out the varchar field, it returns in less than 1 second.
> It took me a while to figure out that it's not a missing index, i can't
> figure this one out.
> please advise.
> rafael