U-SQL Joins

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U-SQL Joins

Steve Jones - SSC Editor

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September 26, 2016 at 10:12 pm

#100938

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September 27, 2016 at 7:06 am

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Ed Wagner SSC Guru Points: 287026 More actions · Answer 1

At this point, there are 196 attempts, 53% correct and no comments. I must not be the only one who don't know much about U-SQL. 😛

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akljfhnlaflkj SSC Guru Points: 76202 More actions · Answer 2

OK, had to look it up. I didn't know anything about U-SQL. Still don't really.

Beatrix Kiddo SSC-Dedicated Points: 32407 More actions · Answer 3

Hah, I chose the most outlandish answer, and it was correct.

TomThomson SSC Guru Points: 104773 More actions · Answer 4

Interesting question.

Microsoft documentation says that U-SQL uses the explicit ANSI SQL join syntax. But there's no actual join syntax in SQL 92 or SQL 99 for SEMIJOINs, they have to be coded using something else (as it does in T-SQL). But the Microsoft U-SQL documentation is pretty sparse, it doesn't mention semiloins or antisemijoins. The best documentation I've found is on this website: Mike McQuillan's article on joins in U-SQL referenced in the explanation for today's QoTD, and even that is rather sparse on semijoins, although not as sparse as the Microsoft doc. I wonder if that stairway will bring more detail on U-SQL join syntax in a future article.

Tom

Jacob Wilkins One Orange Chip Points: 27976 More actions · Answer 5

The detail on JOINs is in a different section from the one you cited, "U-SQL SELECT Selecting from Joins", one level down the tree from the "U-SQL SELECT FROM Clause".

That seemed pretty thorough (and it's the same MS link referenced in the QotD, https://msdn.microsoft.com/en-us/library/azure/mt621318.aspx).

There are even separate pages illustrating the use of the various join types, e.g, https://msdn.microsoft.com/en-us/library/azure/mt621353.aspx and https://msdn.microsoft.com/en-us/library/azure/mt621330.aspx.

Cheers!

Revenant SSC-Forever Points: 42467 More actions · Answer 6

This is still undocumented and Azure Data Lake is still in preview. I had to ask guys on the ADL team to get the correct answer.

Jacob Wilkins One Orange Chip Points: 27976 More actions · Answer 7

Revenant (9/28/2016)
This is still undocumented and Azure Data Lake is still in preview. I had to ask guys on the ADL team to get the correct answer.

Really? Is the documentation I linked to chopped liver? 😀

Cheers!

Koen Verbeeck SSC Guru Points: 259105 More actions · Answer 8

Nice question. Glad that they don't support the FROM A,B WHERE A.ID = B.ID syntax monstrosity.

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Revenant SSC-Forever Points: 42467 More actions · Answer 9

Jacob Wilkins (9/28/2016)
Revenant (9/28/2016)
This is still undocumented and Azure Data Lake is still in preview. I had to ask guys on the ADL team to get the correct answer.
Really? Is the documentation I linked to chopped liver? . . .

Note that most ADL documentation was updated and reposted this week.

For example, this is the first public doc on ADL paths:

https://azure.microsoft.com/en-us/documentation/articles/data-lake-analytics-get-started-net-sdk/

dstrickrott SSCommitted Points: 1951 More actions · Answer 10

Nice question on something new (for me, anyway). Thanks Steve.