To much use of parenthesis (optimizer)

Question

To much use of parenthesis (optimizer)

Calico

Old Hand

Points: 372
More actions
January 13, 2006 at 2:45 pm

#96438

Hi,
If we use to much parenthesis in our query (see beleow), does the optimiser are going to ignore thoses parenthesis and generate a good plan ? Or does the performance of the query are going to be affected ?

FROM   ((((…………..
           LEFT OUTER JOIN……         ON
           (…………..     = ……………))

           LEFT OUTER JOIN …….       ON
           (……………   = …………….) AND
           (……………. = …………….))

           LEFT OUTER JOIN ……… ON
           (……………. = ……………))

           LEFT OUTER JOIN ………. ON
           (…………..   = ……………..) AND
           (…………… = …………….) AND
           (…………… = …………….) AND
           (……………..= …………….'))

thank you
Danny (calico)

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John Rowan SSC Guru Points: 56440 More actions · Answer 1

Why are there parenthesis around the join columns? I shouldn't make a difference in the execution plan. Try stripping out the unneeded parenthesis and comparing the exectution plans and runtime statistics.

John Rowan

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Lowell SSC Guru Points: 323518 More actions · Answer 2

i've seen programs which generate code based on user selections build queries like this....i would guess just running it thru query analyzer and having the show plan on would let youy see whether it affects the query:

paste the query into a query window, do CONTROL+K to turn on show executtion plan and run it;

compare it to the way you would write it normally and do the same thing...look for differences betweent eh two plans.

Lowell

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