IN Vs INNER JOIN

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IN Vs INNER JOIN

purushottam2

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March 7, 2013 at 1:21 am

#271179

Which one is more performance oriented query?
1. SELECT 1 FROM table1 WHERE Id IN (SELECT Id FROM table2)
2. SELECT 1 FROM table1 t1 INNER JOIN table2 t2 ON t1.Id = t2.Id

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Dung Dinh SSCrazy Points: 2513 More actions · Answer 1

purushottam2 (3/7/2013)
Which one is more performance oriented query?
1. SELECT 1 FROM table1 WHERE Id IN (SELECT Id FROM table2)
2. SELECT 1 FROM table1 t1 INNER JOIN table2 t2 ON t1.Id = t2.Id

It depends on

1 - If the table2 is small, you can use 1 or 2

2 - If both are big, you should use second solution and index the columns on ON clause

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

purushottam2 (3/7/2013)
Which one is more performance oriented query?
1. SELECT 1 FROM table1 WHERE Id IN (SELECT Id FROM table2)
2. SELECT 1 FROM table1 t1 INNER JOIN table2 t2 ON t1.Id = t2.Id

http://sqlinthewild.co.za/index.php/2010/01/12/in-vs-inner-join/[/url]

^{“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

Gail Shaw SSC Guru Points: 1004504 More actions · Answer 3

Dung Dinh (3/7/2013)
2 - If both are big, you should use second solution and index the columns on ON clause

Not true.

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

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

purushottam2 SSCrazy Points: 2021 More actions · Answer 4

purushottam2

SSCrazy

Points: 2021

March 7, 2013 at 2:10 am

#1594340

May i know the cause?

Kingston Dhasian SSCoach Points: 19799 More actions · Answer 5

purushottam2 (3/7/2013)
May i know the cause?

The cause is present in the link provided by Chris earlier in the thread and also provided below

http://sqlinthewild.co.za/index.php/2010/01/12/in-vs-inner-join/

Kingston Dhasian

How to post data/code on a forum to get the best help - Jeff Moden
http://www.sqlservercentral.com/articles/Best+Practices/61537/

Dung Dinh SSCrazy Points: 2513 More actions · Answer 6

GilaMonster (3/7/2013)
Dung Dinh (3/7/2013)
2 - If both are big, you should use second solution and index the columns on ON clause
Not true.

I mean that the second is preferred in this case. Of course, If we would like to be sure, we need to record performance on both of IN and INNER JOIN base on your environment.

In my case, I often select INNER JOIN as the first while working with large tables and check indexes. After that, record performance to compare.

Gail Shaw SSC Guru Points: 1004504 More actions · Answer 7

Dung Dinh (3/7/2013)
GilaMonster (3/7/2013)
Dung Dinh (3/7/2013)
2 - If both are big, you should use second solution and index the columns on ON clause
Not true.
I mean that the second is preferred in this case.

The first is the preferred option in all cases, it's less work and if all you're doing is checking for existence of a row in another table then IN/EXISTS is the logical operation to use as that's exactly what it does.

Inner join checks, joins and fetches both rows, it'll cause duplicate rows if there's more than one matching row (in won't) and it's more work since it's a full join instead of a semi-join

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

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

Stuart Davies SSCoach Points: 19505 More actions · Answer 8

From the above (and Gails article) it looks like "in" has the advantage.

I'm not dissenting with any previous replies, but personally I would check the results before changing any production code.

Try it on a test system with the real table structure, indexes, data etc.

Compare the execution plans (actual not estimated) for your setup and see which is the most efficient.

-------------------------------Posting Data Etiquette - Jeff Moden [/url]Smart way to ask a question
There are naive questions, tedious questions, ill-phrased questions, questions put after inadequate self-criticism. But every question is a cry to understand (the world). There is no such thing as a dumb question. ― Carl Sagan
I would never join a club that would allow me as a member - Groucho Marx

Gail Shaw SSC Guru Points: 1004504 More actions · Answer 9

Stuart Davies (3/7/2013)
I'm not dissenting with any previous replies, but personally I would check the results before changing any production code.
Try it on a test system with the real table structure, indexes, data etc.
Compare the execution plans (actual not estimated) for your setup and see which is the most efficient.

Don't compare execution plans, compare performance characteristics. You can't tell from a comparison of exec plans which query absolutely will be faster, the costs are estimates, they can easily be wrong.

My general guidelines: Write the query to do just what you want in the simplest way possible, so if you're looking to see if rows match, use exists/in, if you're looking to retrieve columns from both tables, use join. Test the code. If it performs unacceptably under expected load, then go looking for tricks, alternatives and fancy methods

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

We walk in the dark places no others will enter
We stand on the bridge and no one may pass

Stuart Davies SSCoach Points: 19505 More actions · Answer 10

Thanks for the reminder of performance characteristics v exec plans - my bad memory

-------------------------------Posting Data Etiquette - Jeff Moden [/url]Smart way to ask a question
There are naive questions, tedious questions, ill-phrased questions, questions put after inadequate self-criticism. But every question is a cry to understand (the world). There is no such thing as a dumb question. ― Carl Sagan
I would never join a club that would allow me as a member - Groucho Marx