Tuning SP (Left Outer Join)

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Tuning SP (Left Outer Join)

ramana3327

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Points: 19722
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March 21, 2014 at 8:21 am

#283659

Hi,
I am working on tuning of sp. They wrote several left outer join. Is there any option to avoid them. Any suggestions please

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

Without any clue on what the desired output is, how the query looks like et cetera, this question is impossible to answer.

You might get rid of your LEFT OUTER JOINS, if an INNER JOIN suffices.

However, LEFT OUTER JOINS are not necessarily bad.

ps: your question looks like this: "Hi, I need to travel to London, can you give me directions?" But we have no idea where you currently are. Are you near London or even in the United Kingdom at all?

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

ramana3327 (3/21/2014)
Hi,
I am working on tuning of sp. They wrote several left outer join. Is there any option to avoid them. Any suggestions please

Left joins are a logic decision, too frequently a defensive decision. Can you tell which type of left join these are? If you can't, then hire a specialist.

^{“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

Grant Fritchey SSC Guru Points: 398890 More actions · Answer 3

If, logically, you need all the rows from one table, but only the matching rows from another table, then some type of OUTER JOIN is necessary. They're not inherently evil.

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