Friday, February 17, 2012

Efficiency with INNER JOINs

Hi,
Is there an efficiency issue with INNER JOINs? For example, is there a
difference betweeen tableA INNER JOIN tableB and tableB INNER JOIN tableA?
What's the performance doing tableA INNER JOIN tableB INNER JOIN tableC etc?
Thanks,
Mats-LennartMats
> Is there an efficiency issue with INNER JOINs? For example, is there a
> difference betweeen tableA INNER JOIN tableB and tableB INNER JOIN tableA?
>
Actually there is no difference. The optimizer will choose the order to join
tables.
> What's the performance doing tableA INNER JOIN tableB INNER JOIN tableC
> etc?
>
I have always tried to create an index on foreign key column ( participate
in JOIN) to improve performance
http://www.sql-server-performance.com/tuning_joins.asp
"Mats-Lennart Hansson" <ap_skallen@.hotmail.com> wrote in message
news:%23RygRo2OGHA.1288@.TK2MSFTNGP09.phx.gbl...
> Hi,
> Is there an efficiency issue with INNER JOINs? For example, is there a
> difference betweeen tableA INNER JOIN tableB and tableB INNER JOIN tableA?
> What's the performance doing tableA INNER JOIN tableB INNER JOIN tableC
> etc?
> Thanks,
> Mats-Lennart
>|||Differnent writing of the queries often doesn=B4t interfer the
performance difference in query, though the query pocessor and
optimizer will make a plan on his own which tabe to query first and so
on to get the best performance for your statement.
HTH, Jens Suessmeyer.

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