URGENT: Question about merge and hash JOIN

Question

Post reply

URGENT: Question about merge and hash JOIN

SQLphone

SSC-Addicted

Points: 433
More actions
December 4, 2009 at 10:06 pm

#385897

Please help me with the following questions ….
1) When joining two small row sets together on an inner join, which join type is generally preferred?
a. Hash Join
b. Merge Join
c. Loop Join
3) What is the difference between a hash join and a merge join?
Thank you.

Viewing 13 posts - 1 through 12 (of 12 total)

You must be logged in to reply to this topic. Login to reply

arun.sas SSChampion Points: 11831 More actions · Answer 1

Hi,

Ref this for your interview questions

http://support.microsoft.com/kb/197297

Gail Shaw SSC Guru Points: 1004504 More actions · Answer 2

Why is this urgent?

http://sqlinthewild.co.za/index.php/2009/11/24/the-most-optimal-join-type/

http://sqlinthewild.co.za/index.php/2007/12/30/execution-plan-operations-joins/

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

SQLphone SSC-Addicted Points: 433 More actions · Answer 3

GilaMonster (12/4/2009)
Why is this urgent?
http://sqlinthewild.co.za/index.php/2009/11/24/the-most-optimal-join-type/
http://sqlinthewild.co.za/index.php/2007/12/30/execution-plan-operations-joins/

Thanks GilaMonster. I have applied for an internship and I was asked the question by an HR person in email. Thats why I said it is urgent.

SQLphone SSC-Addicted Points: 433 More actions · Answer 4

arun.sas (12/4/2009)
Hi,
Ref this for your interview questions
http://support.microsoft.com/kb/197297

Thank You. That was helpful

Gail Shaw SSC Guru Points: 1004504 More actions · Answer 5

daniel.phone (12/5/2009)
Thanks GilaMonster. I have applied for an internship and I was asked the question by an HR person in email. Thats why I said it is urgent.

It's usually faster to hit a search engine than to post here and wait for replies.

Also, please note that, in general, people here won't give you answers to interview questions, they'll give you suggestions on where to look. The logic behind that is that we're not going to give people answers so that they can pass interviews and get jobs that they are not qualified for. We have before had people posting pages of questions from an interview/test

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

Grant Fritchey SSC Guru Points: 398882 More actions · Answer 6

daniel.phone (12/4/2009)
0 vote down
star
Please help me with the following questions as soon as possible….
1) True or False, specifying a join hint will force join order?
2) When joining two small row sets together on an inner join, which join type is generally preferred?
a. Hash Join
b. Merge Join
c. Loop Join
3) What is the difference between a hash join and a merge join?
Thank you.

So, this post was just fishing for answers to interview questions? I'd be very cautious about doing what you've just done to land a job. You don't think that people working at companies can do a search on their favorite questions? Or that they might be hanging out in these same forums? That's a pretty dangerous mechanism you're using to land the job. Some might call it dishonest.

"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt

Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning

SQLphone SSC-Addicted Points: 433 More actions · Answer 7

Grant Fritchey (12/7/2009)
daniel.phone (12/4/2009)
0 vote down
star
Please help me with the following questions as soon as possible….
1) True or False, specifying a join hint will force join order?
2) When joining two small row sets together on an inner join, which join type is generally preferred?
a. Hash Join
b. Merge Join
c. Loop Join
3) What is the difference between a hash join and a merge join?
Thank you.
So, this post was just fishing for answers to interview questions? I'd be very cautious about doing what you've just done to land a job. You don't think that people working at companies can do a search on their favorite questions? Or that they might be hanging out in these same forums? That's a pretty dangerous mechanism you're using to land the job. Some might call it dishonest.

okay..okay..... I got the wrong idea at first and thought fellow experts would just tell me the answer! I got it. It wont happen again.

Grant Fritchey SSC Guru Points: 398882 More actions · Answer 8

daniel.phone (12/7/2009)
Grant Fritchey (12/7/2009)
daniel.phone (12/4/2009)
0 vote down
star
Please help me with the following questions as soon as possible….
1) True or False, specifying a join hint will force join order?
2) When joining two small row sets together on an inner join, which join type is generally preferred?
a. Hash Join
b. Merge Join
c. Loop Join
3) What is the difference between a hash join and a merge join?
Thank you.
So, this post was just fishing for answers to interview questions? I'd be very cautious about doing what you've just done to land a job. You don't think that people working at companies can do a search on their favorite questions? Or that they might be hanging out in these same forums? That's a pretty dangerous mechanism you're using to land the job. Some might call it dishonest.
okay..okay..... I got the wrong idea at first and thought fellow experts would just tell me the answer! I got it. It wont happen again.

Actually, if you go back over to ask.sqlservercentral.com you'll see that I did answer the question, directly, before I found out what it was for. It sounded like homework, but specific enough that I didn't mind providing some information.

"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt

Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning

The Dixie Flatline SSC Guru Points: 53354 More actions · Answer 9

"FELLOW experts???"

__________________________________________________

Against stupidity the gods themselves contend in vain. -- Friedrich Schiller
Stop, children, what's that sound? Everybody look what's going down. -- Stephen Stills

Steve Jones - SSC Editor SSC Guru Points: 736193 More actions · Answer 10

Please do not cross post and please make your own attempt to do work. the "fellow experts" are happy to help, but not do the work for you.

SQLphone SSC-Addicted Points: 433 More actions · Answer 11

Number 6 (12/7/2009)
"FELLOW experts???"

my bad...fellow newbies! 🙂

SQLRNNR SSC Guru Points: 281334 More actions · Answer 12

I think you will find that the advice given by the experts here has been generous.

Many of the people that have responded to you post are Interviewers and influential in the community. As an Interviewer, it is not uncommon practice to background check a candidate, nor to see if that candidate is trying to memorize Q&A for the interview, as well as to check forums to see what kind of involvement that person has in the community, and lastly - many employers will browse the web to see what they can dig up about a candidate regardless of forums or interview Q&A.

When an Interviewer comes across a thread like this, it only hurts your chances of getting that job. If you don't know the information but know how to research the information and do the leg-work that the job requires, it will stand out for the employer and interviewer far more than to post questions in a forum expecting immediate results.

Jason...AKA CirqueDeSQLeil
_______________________________________________
I have given a name to my pain...MCM SQL Server, MVP
SQL RNNR
Posting Performance Based Questions - Gail Shaw[/url]
Learn Extended Events