Query optimization

Question

Query optimization

Aadhar Joshi

Hall of Fame

Points: 3202
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December 12, 2012 at 12:35 am

#267416

Hello,
I have two tables
#InnerTable which have around 7000 rows
DCl.CompanyToken which have around 20000000 rows
when i am firing below query, it takes around 30 mins to execute and return 787 rows..
please help to optimize it
SELECT
a.SearchTokenNumber ,
a.SearchRowID ,
CT.CompanyID ,
CT.CompanyRowID ,
a.SearchField ,
a.MaxPossibleScore ,
a.AssignedWeight ,
MAX(a.Weight) Weight
FROM
#InnerTable a
INNER JOIN DCl.CompanyToken CT ON a.CompanyTokenNumber = CT.CompanyTokenNumber
WHERE AND CT.Token = a.Token
GROUP BY a.SearchTokenNumber ,
a.SearchRowID ,
CT.CompanyID ,
CT.CompanyRowID ,
a.SearchField ,
a.MaxPossibleScore ,
a.AssignedWeight
Note..
CREATE INDEX IX_LocalIdentifierID ON #InnerTable (CompanyTokenNumber) index is applied on #InnerTable.
/****** Object: Index [ix_CL_DCL_CompanyToken] Script Date: 12/12/2012 13:04:19 ******/
CREATE CLUSTERED INDEX [ix_CL_DCL_CompanyToken] ON [DCL].[CompanyToken]
(
[CompanyTokenNumber] ASC,
[Token] ASC,
[CompanyID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
index is applied on DCl.CompanyToken

Viewing 12 posts - 1 through 11 (of 11 total)

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Koen Verbeeck SSC Guru Points: 259115 More actions · Answer 1

Can you post the actual query plan?

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Gail Shaw SSC Guru Points: 1004504 More actions · Answer 2

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

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Aadhar Joshi Hall of Fame Points: 3202 More actions · Answer 3

Aadhar Joshi

Hall of Fame

Points: 3202

December 12, 2012 at 1:40 am

#1567744

Please find attachment

Thanks,

Aadhar

nigelrivett SSCertifiable Points: 5472 More actions · Answer 4

How many rows does it need to access in the large table - is it most of them or a few.

Are the group by columns independent? Can some be omitted from the group by and a max used in the resultset - i.e. if you omit some any column from the group by clause will you always get less groups?

Cursors never.
DTS - only when needed and never to control.

Aadhar Joshi Hall of Fame Points: 3202 More actions · Answer 5

large table has 20000000 rows and all group by are required

By ommiting single group by will raise me to an error..

nigelrivett SSCertifiable Points: 5472 More actions · Answer 6

The large table has that many rows but are they all involved in the join to the temp table or does that join filter the rows accessed and if so by how much. If you only require a few thousand rows from the large table it could help to split the query into two.

Removing a column from the group by will give an error unless you aggregate the column in the select clause by using (e.g.) max()

So if you remove a.AssignedWeight from the group by clause and change the entry in the select clause to max(a.AssignedWeight) do you get less entries returned or is a.AssignedWeight dependent on the other values?

Cursors never.
DTS - only when needed and never to control.

Aadhar Joshi Hall of Fame Points: 3202 More actions · Answer 7

This is what u are telling same thing.

If i split query and i take sub data and group it or i take temp table to store partial data and use it to further join, It will take same time.

I tried but couldnt succeed.

nigelrivett SSCertifiable Points: 5472 More actions · Answer 8

Do you want to answer the questions I asked?

Cursors never.
DTS - only when needed and never to control.

Aadhar Joshi Hall of Fame Points: 3202 More actions · Answer 9

Aadhar Joshi

Hall of Fame

Points: 3202

December 12, 2012 at 4:09 am

#1567805

I tried but it produces less rows..

Sean Pearce SSCoach Points: 15999 More actions · Answer 10

Have you updated stats? You have some serious under-estimations with the large table.

Clustered Index Seek

[DS_GreensDK].[DCL].[CompanyToken].[ix_CL_DCL_CompanyToken]

Estimated Number Of Rows : 309

Actual Number Of Rows : 13,807,291

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Aadhar Joshi Hall of Fame Points: 3202 More actions · Answer 11

No i haven not updated stats..

May b i'll have to check that..