Performance tuning on insert query

Question

Performance tuning on insert query

splinter-740692

SSC Eights!

Points: 901
More actions
June 17, 2010 at 3:04 am

#236604

Hi all,
I have a validation table which gets updated through a insert statement. The fields in the select clause has a computed column and the t_validate table gets updated once matching policies and other conditions are satisfied.
Now This query in previuos runs would complete in 5 mins. But now it is taking more than 2 hours and still query does not complete. For information, this step is taking longers hours as additional data has been added to table b (> 1 mil records).
Please help to optimize this query. Thanks....
Actual query:
insert into t_validate (policy,form,date,premium)
Select a.policy, a.form, a.date, sum(a.premium/b.premprcnt) as premium
from b inner join a on
b.policy = a.policy and
b.form = a.form and
b.date = a.date and
b.location_date = a.location_date and
b.location_pin = a.location_pin and
b.state = a.state
group by a.policy, a.form, a.date

Viewing 7 posts - 1 through 6 (of 6 total)

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Gail Shaw SSC Guru Points: 1004504 More actions · Answer 1

Please post table definitions, index definitions and execution plan as per http://www.sqlservercentral.com/articles/SQLServerCentral/66909/

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

ChrisM@Work SSC Guru Points: 186127 More actions · Answer 2

How long does the select part SELECT

a.policy,

a.form,

a.date,

SUM(a.premium/b.premprcnt) AS premium

FROM b

INNER JOIN a

ON b.policy = a.policy

AND b.form = a.form

AND b.date = a.date

AND b.location_date = a.location_date

AND b.location_pin = a.location_pin

AND b.state = a.state

GROUP BY a.policy, a.form, a.date of the query take to run?

^{“Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw}

For fast, accurate and documented assistance in answering your questions, please read this article.
Understanding and using APPLY, (I) and (II) Paul White
Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden

splinter-740692 SSC Eights! Points: 901 More actions · Answer 3

It takes more than 2 hours. I have let the query run completely. I cancelled the query once it crossed the 2 hour duration.

Gail Shaw SSC Guru Points: 1004504 More actions · Answer 4

Can you post the things I asked for?

Is this supposed to be an unrestricted select? No where clause?

Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

Grant Fritchey SSC Guru Points: 398890 More actions · Answer 5

Gail may have already spotted the problem. If you're just running the SELECT and there's no filter on the data, it's doing a scan of all data across all the tables involved in the query. It's just going to take how long it takes. You might be able to speed up aspects of it such as the joins, with indexing, but overall... you might be in trouble.

"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt

Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning

Stefan_G SSCertifiable Points: 6609 More actions · Answer 6

To get maximum performance you want a merge join between a and b and you want an index on a so you can use a stream aggregation for the group by.

This can be achieved by using the following indexes:

create nonclustered index IX_a on a

(policy, form, date, location_date, location_pin, state)

include (premium)

create nonclustered index IX_b on b

(policy, form, date, location_date, location_pin, state)

include (premprcnt)