Query on optimization

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Query on optimization

RockingAdmin

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Points: 2828
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March 7, 2010 at 5:14 am

#219652

hi
i have a SQL query having inner join with 8 tables, now i am using stored procedure to get results of that query. in the production enviromment, with these many table joins it will kill performance. is there any other way to handle these kind of SQL
Queries...
Thanks
Rock..

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Lowell SSC Guru Points: 323504 More actions · Answer 1

there's a lot of factors in optimization; you'd really want to attach the execution plan here to get any really significant answers.

are all your joins on PK to FK relationsships?

I'm under the impression that you might benefit from putting an index on the FK column of the child table if there are a lot of rows in the child table; (8000?), as if there is more than a page of joins, the index can help.

a lot of times, the joins are not the issue, but the filtering done by the WHERE statements; arguments that are not SARGable cause table scans instead of using indexes for seeks or scans, and that's probably the most common cause of low performing queries.

Lowell

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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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FabricioLimaDBA Mr or Mrs. 500 Points: 507 More actions · Answer 3

Hi, Can you put your query here?

Fabrício França Lima
MCITP – Database Administrator
https://www.fabriciolima.net/Blog

Grant Fritchey SSC Guru Points: 398690 More actions · Answer 4

An 8 table join is not going to kill performance assuming the query is well written and the indexes are properly structured. A 40 table join won't kill performance (trust me on that one, but an 80 table join can, but because of compile time, not query performance). There is no magic number of tables in a join that lead to bad performance.

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