What is a Merge Join Operator?

This this video you will learn what a merge join operator is when you see one in an execution plan.

I'm currently working for FM Global, an industry leading engineering & insurance company, as a DBA. I've done development of large scale applications in languages such as VB, C# and Java. I've worked in SQL Server from the hoary days of 6.0. My nickname at work is the "The Scary DBA." I even have an official name plate with it. I wear it proudly. I was awarded a Microsoft MVP in April of '09.

James Mount on 10/16/2008

Video was broken - jumps in at the end. I would love to see the entire merge join operator video.

Chris Rock on 10/16/2008

James, I did not see any problems with the video. If you could send an email to webmaster@jumpstarttv.com with the issue you're having we'd be happy to help you out.

DavidB on 10/16/2008

Good information about the join operator but it would be good to discuss how to avoid them or what to look for with these that could be potentially costly to your database engine with these operators.

Benjamin Lotter on 10/16/2008

It didn't explain how to write queries to leverage the Merge join. For example, how do the tables and joins against those tables need to look?

hades on 10/16/2008

What do you mean by "Sorted" Id on;t see an order by clause. Do you mean that the two tables being joined have indexes??

Grant Fritchey on 10/16/2008

The data is sorted because it's being pulled from indexes, which sort data, directly. If there had been other operations between the index scan operations and the merge, it would have had to put a sort operation in.

TomC on 10/16/2008

But very limited. Would like to see an example of a Merge Join that is not tied to indexes and what you might consider doing.

Tahir A. Syed on 10/27/2008

Short but enough Thanks

Richard Rosenberg on 10/27/2008

Good but incomplete

8A7E4A6C54 on 11/6/2008

Learnt something new here

datamama on 4/27/2009

needed more explanation - especially what would cause a 'bad' Merge Join

Joe on 7/10/2009

Merge joins are the best was very clearly stated

Fernando Garcia on 7/29/2009

Hi i´m from brazil,congratulations about this video,it was very objective.

kin on 9/8/2009

good stuff. got more?

Deborah Land on 5/19/2010

Doesn't start at the beginning.

Steven Robinson on 12/30/2011

Very good