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Category: T-SQL Tuesday

Deleting SSAS Cube Partitions With Powershell

Published 2017-09-12 by Kevin Feasel

Richie Lee shows how to remove Analysis Services cube partitions using Powershell:

One such an example of ad-hoc DBA tasks was when I had to delete about 600 partitions from a measure group that had thousands of partitions. Doing this manually would be ridiculous, so at the time I created a SQL script that used some dynamic T-SQL to create the delete commands in XMLA. XMLA has no “delete if exist” type syntax, so if I needed to run this again, this dynamic SQL output wouldn’t work. And so I decided that if I had to run the same task a gain I would write a PowerShell script that would run DSC-style and drop the partitions that were no longer required. And funnily enough, that is exactly what I had to do.

I knew I would be able to create a Powershell script that used AMO to check if a partition exists and drop it if it did. I also wanted the script to take into account any other partitions in other measure groups that may also need to be dropped. So I made sure the script uses PowerShell switches that can be included when calling the function, and if they are included then the pertaining partitions in that measure group will be deleted. So you can run the script for one, some or all of the measure groups in a cube.

Click through for the script.

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Starting Out With Powershell

Published 2017-09-12 by Kevin Feasel

Rob Sewell has his own introduction to Powershell:

PowerShell is another language, you are not going to be as proficient in a new language as you are in the language you spend all day working with. You will have to go through the learning curve and you will have to understand how to interpret errors. There is a learning curve just like with any language. Undoubtedly you will get frustrated at times. Reach out for help. Use twitter, use the #powershellhelp in the SQL Server Community Slack channel. There are many other places and plenty of people who will be glad to help you.

Rob has a pretty detailed introduction to the topic, so it’s well worth the read for new Powershell users.

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Getting Started With Powershell

Published 2017-09-12 by Kevin Feasel

Rob Farley gives us a basic introduction to Powershell:

I want to take a few minutes to get you started with PowerShell, in a way that I think is less overwhelming than how I found most PowerShell material back in the day. Because you’ve told me you keep hearing about PowerShell, and that you can’t tell how to get into it.

The first thing to know is that it feels like Command Prompt on steroids, but a lot more useful than Command Prompt. You’ll see what I mean as soon as you open it. Let’s do that, but let’s open it using ‘Run as Administrator’, because that just helps for some of the demos. In real life, you’ll only open it with Admin rights if you really need to.

So click on the start button and start typing PowerShell. I don’t want you to open the ISE (yet), just find the “Windows PowerShell” shortcut, and right-click on it to choose ‘Run as Administrator’.

This T-SQL Tuesday is all about Powershell, and Rob’s is one of the first posts you should read if you’re not familiar.

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T-SQL Tuesday Roundup

Published 2017-08-15 by Kevin Feasel

Kendra Little rounds up the latest T-SQL Tuesday:

I’m glad I picked interviewing as the topic of TSQL Tuesday #93, because people wrote posts chock full of great advice and funny stories. Get ready to learn, be amazed, and laugh out loud as you read these posts, which I’ve indexed by the author’s first name. Don’t blame these authors for the dorky jokes in the cartoons, though. That’s all my fault.

Read on for a few dozen interview stories and some of Kendra’s one-liner cartoons.

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T-SQL Tuesday 92 Roundup

Published 2017-08-01 by Kevin Feasel

Raul Gonzalez wraps up T-SQL Tuesday #92:

On July 2017’s event the proposed topic was aimed for all you to share those little secrets that made your tummy burn after pressing F5.

Since early in the morning I’ve been reading your posts which makes me very happy and feel the topic was certainly well accepted by the community.

In order of published date these are the posts that took part in this month’s event.

Click through to see the 17 entries this month.

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Check Where That Backup’s Restoring To

Published 2017-07-12 by Kevin Feasel

Shane O’Neill “has a friend” who learned an important lesson about the database restore GUI:

GUIs are good for….

…discovery.

They give you the option to script out the configurations you have chosen. If my friend had chosen to script out the restore, rather then clicking “OK” to run it, maybe he would have caught this mistake when reviewing it – rather than overwriting the Live database with 2 week old data and spending a weekend in the office with 3 colleagues fixing it.

Plus if you ever want to ensure that you know something, try and script it out from scratch.

Read the whole thing; good thing that totally didn’t happen to Shane and was just his friend!

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Save Early, Save Often

Published 2017-07-12 by Kevin Feasel

Kenneth Fisher relays an important life lesson:

So years and years ago, when I was in college, one of my favorite classes was Assembly Language. We were working with Mac Assembly in case anyone is interested (yes I used a Mac at school, one of the big ones that had the monitor built into it). Somewhere around week three or four, we were supposed to print something to the screen. I spent several hours (this was only my second programming class so even Hello World was a challenge) and got my program ready to test. It worked! Sort of.

Hello World was written to the top of the screen! Then a second or so later the bottom half of the screen turned into random ASCII garbage. Then a second or so later the computer rebooted. Well, that’s not good. Time to debug!

So the computer comes back up, I take a look, and I don’t have ANY code. I hadn’t saved (and this was long enough ago there was no auto-save). I had to start ALL over again. In the end, I did manage to re-write my code, got it working and even got an A. I also learned that I needed to save my work before running it. Well, learned my lesson for the first time (of many).

I have attempted to put a sanguine spin on this mishap, based on something Phil Factor once wrote:  if you throw away (or lose) the code the first time around, the second time you write it, the code will probably be better.  This is because the first time you’re writing a set of code, you’re trying to force the pieces together and get the code working; the second time around, you have a working algorithm in mind, so the code will likely be much cleaner.

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Watch Those Indexes

Published 2017-07-11 by Kevin Feasel

Kennie Nybo Pontoppidan explains why that one university registration system was always throwing errors:

Remember that myITU was implemented on an Oracle database. Unlike on SQL Server, all tables in an Oracle database are physically represented as heaps, unless explicitly specified otherwise. That means no indexes. And I didn’t know anything about database performance back then, so I didn’t add any. Effectively any query against the course table would give a full table scans in the EnumerationType and EnumerationValue tables as a side effect. Fast forward to course enrolments…

At ITU, we had implemented a selection algorithm, which considered both the study program you were enrolled into as well as how early you registered for a course. Early birds got the course, so students would be ready when course enrolment was opened at 12pm. And at 12.05 myITU would start failing with 500 Internal Server Errors.

This is a pretty common occurrence, followed up by the “let’s add all the indexes” phase.

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Life Lessons Learned

Published 2017-07-11 by Kevin Feasel

Andy Levy shares a few lessons learned from painful experience:

A couple of times, I’ve had under-performing VMs running SQL Server. As I hadn’t been involved in the configuration, I thought everything had been provisioned properly. Turns out…not so much. Memory reservations, storage configuration, power profiles, all set up for suboptimal performance.
Lesson learned: Ask your VMWare admin if they’ve perused the best practices guide and review things yourself before going down the rabbit hole of SQL Server configuration & query tuning. If the underlying systems aren’t configured well, you’ll spin your wheels for a long time.

Read on for more lessons.

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