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Are the posted questions getting worse? Expand / Collapse
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Posted Tuesday, June 24, 2014 1:24 PM
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Koen Verbeeck (6/24/2014)
Luis Cazares (6/24/2014)
Congratulations Koen. You're certainly one of the top posters on Bi.
On a completely different subject, I'm taking 20467BC course this week and found some surprises like using while loops to create sample data, recommendations to use partitioning for performance and nolock hints on every view in the data warehouse to prevent concurrency issues.
Are they serious? Should I unlearn something?


Partitions do improve insert performance. Might help for very large fact tables.
And you also have the partition eliminiation when querying, but I haven't noticed that much performance improvement.


Partitions can improve some performance in limited scenarios. It isn't something I'd suggest for every database.
I don't think I agree with any of the suggestions the course is giving. Tally tables for sample data or cross joins on sys tables and I'd stay away from NOLOCK whenever possible if only to discourage its use among people who don't understand the risks.


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Post #1585646
Posted Tuesday, June 24, 2014 4:14 PM


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Luis Cazares (6/24/2014)
On a completely different subject, I'm taking 20467BC course this week and found some surprises like using while loops to create sample data, recommendations to use partitioning for performance and nolock hints on every view in the data warehouse to prevent concurrency issues.
Are they serious? Should I unlearn something?

If the data warehouse is being queried while it's static - ie not while data is being added to the tables being queried - it's appropriate to use SET TRANSACTION ISOLATION LEVEL READ UNCOMITTED. Only if there are some tables which are effectively static and others that are not is it appropriate to use nolock hints. Of course if the error caused by dirty reads on some tables is harmless you can count those tables as static even if they aren't.


Tom
Post #1585713
Posted Tuesday, June 24, 2014 5:31 PM


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WHOOP!

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Post #1585719
Posted Wednesday, June 25, 2014 5:00 AM


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Just saw a post (on another site) that the person had part of a query list but no quest was asked. Someone posted "What is your question?" and the post back "It's in my original post." It was not.
Post #1585821
Posted Wednesday, June 25, 2014 5:12 AM
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TomThomson (6/24/2014)
Luis Cazares (6/24/2014)
On a completely different subject, I'm taking 20467BC course this week and found some surprises like using while loops to create sample data, recommendations to use partitioning for performance and nolock hints on every view in the data warehouse to prevent concurrency issues.
Are they serious? Should I unlearn something?

If the data warehouse is being queried while it's static - ie not while data is being added to the tables being queried - it's appropriate to use SET TRANSACTION ISOLATION LEVEL READ UNCOMITTED. Only if there are some tables which are effectively static and others that are not is it appropriate to use nolock hints. Of course if the error caused by dirty reads on some tables is harmless you can count those tables as static even if they aren't.


And when the cube processing fails, where are you going to find the (harmless) error?
Post #1585827
Posted Wednesday, June 25, 2014 5:18 AM


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djj (6/25/2014)
Just saw a post (on another site) that the person had part of a query list but no quest was asked. Someone posted "What is your question?" and the post back "It's in my original post." It was not.


That happens here too. And developers are always whingeing that the specs they are given don't contain sufficient information to complete the task. Gaaah!


“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
Exploring Recursive CTEs by Example Dwain Camps
Post #1585834
Posted Wednesday, June 25, 2014 5:25 AM


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djj (6/25/2014)
Just saw a post (on another site) that the person had part of a query list but no quest was asked. Someone posted "What is your question?" and the post back "It's in my original post." It was not.


Sounds familiar.
A while back I encountered one of these "questions":
"Hi, I want to do X. Here is a query that I have written."

So we just have to guess what the problem is apparently.

Sometimes they add "It doesn't work".
What doesn't work??? Does the query give an error? Or does it return results that are not expected? Did your computer implode? Did the query become consciousness-aware and it tried to take over the world? What happened???

*rant off*




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Post #1585835
Posted Wednesday, June 25, 2014 5:26 AM


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ChrisM@Work (6/25/2014)
djj (6/25/2014)
Just saw a post (on another site) that the person had part of a query list but no quest was asked. Someone posted "What is your question?" and the post back "It's in my original post." It was not.


That happens here too. And developers are always whingeing that the specs they are given don't contain sufficient information to complete the task. Gaaah!


Right.
Or when you propose a solution and they go like "Aaaah yes. But actually in my real-life scenario I need to do it like this..."




How to post forum questions.
Need an answer? No, you need a question.
What’s the deal with Excel & SSIS?

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Post #1585836
Posted Wednesday, June 25, 2014 6:17 AM


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Koen Verbeeck (6/25/2014)
ChrisM@Work (6/25/2014)
djj (6/25/2014)
Just saw a post (on another site) that the person had part of a query list but no quest was asked. Someone posted "What is your question?" and the post back "It's in my original post." It was not.


That happens here too. And developers are always whingeing that the specs they are given don't contain sufficient information to complete the task. Gaaah!


Right.
Or when you propose a solution and they go like "Aaaah yes. But actually in my real-life scenario I need to do it like this..."
I had forgotten about that one
Post #1585852
Posted Wednesday, June 25, 2014 6:57 AM
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djj (6/25/2014)
Koen Verbeeck (6/25/2014)
ChrisM@Work (6/25/2014)
djj (6/25/2014)
Just saw a post (on another site) that the person had part of a query list but no quest was asked. Someone posted "What is your question?" and the post back "It's in my original post." It was not.


That happens here too. And developers are always whingeing that the specs they are given don't contain sufficient information to complete the task. Gaaah!


Right.
Or when you propose a solution and they go like "Aaaah yes. But actually in my real-life scenario I need to do it like this..."
I had forgotten about that one
There are many ways people can post questions poorly. They can omit the question, omit the DDL and data, say that they have a problem but can't post it because it's sensitive, or simply post a query with no other explanation. They can do one or more of the above. They can then get snippy when asked for more information or talk like you're a complete moron because you don't understand the question they didn't ask.

You know, the quality of the question directly impacts the quality of the answer. Except for Lynn, who somehow manages to take a shot in the dark and somehow hit the nail right on the head.



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Post #1585873
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