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Category: Analysis Services

Limitations Of Object-Level Security In Tabular Models

Published 2018-04-18 by Kevin Feasel

Teo Lachev gives us the skinny on object-level security in an Analysis Services Tabular model:

Object-level security (OLS) is a frequently requested security feature when implementing semantic models. For example, a current project disallows some sales persons to see sensitive measures, such as Margin and Profit. In Multidimensional, modelers could use cell security to meet such requirements with the risk of compromising performance. Starting with SQL Server 2017 (compatibility level 1200), Tabular supports object-level security to disallow access to entire tables or specific columns without a performance penalty. As it stands, OLS has the following limitations (for a full list, review the documentation):

Click through for the list of limitations.

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Migrating Excel Power Pivot Models To SSAS

Published 2018-04-16 by Kevin Feasel

Imke Feldmann has a walkthrough to show how to migrate a Power Pivot model in Excel into SQL Server Analysis Services by way of Power BI:

In Visual Studio there is a wizard to migrate an Excel Power Pivot model to a SSAS model. But this will not bring over the M-queries unfortunately. But there is a workaround to achieve this. It requires SQL Server 2017 or higher.

Click through for a list of operations and a video showing how it’s done.

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Azure Analysis Services Parallelism And Scale

Published 2018-04-05 by Kevin Feasel

Teo Lachev has a quick note on Azure Analysis Services and parallelism:

Anyone who’s done parallel programming knows that it’s not easy. Safe access and locks need to be used to synchronize access and protect shared resources. The AS xVelocity engine (aka Vertipaq) is a multi-threaded application that accesses RAM as a shared resource. As each thread competes for a global lock for memory allocation/deallocation, scalability decreases. Because processor cores reserve memory in chunks, called cache lines, additional synchronization is required when threads access memory location that are close to each other. Before SQL Server 2016 SP1, this was a serious issue with Tabular. As we’ve learned, starting with SQL Server 2016 SP1, Microsoft switched to using the Intel Threading Building Clocks (TBB) C++ library. Specifically, Tabular now uses the TBB scalable memory allocator. Mind you that TBB is not CPU-specific extensions, so any modern Intel CPU should get these benefits. “Analysis Services SP1 uses an Intel TBB-based scalable allocator that provides separate memory pools for every core. As the number of cores increases, the system can scale almost linearly” and “The Intel TBB-based scalable allocator is also expected to help mitigate performance problems due to heap fragmentation that have been shown to occur with the Windows Heap”. Further, starting with SP1, Tabular is NUMA aware with 4-node NUMA system but I don’t know if the AAS VMs are preconfigured for NUMA.

Teo doesn’t have any firm conclusions at this point, but his initial testing looks positive.

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Error Running Analysis Services Processing Task

Published 2018-03-05 by Kevin Feasel

Angela Henry ran into a problem with the SSIS Analysis Services processing task:

In both of these scenarios you will not be able to save the package.  So what the heck are you supposed to do?!  Here’s where my tunnel vision (and panic) sets in.  How was I supposed to get my SSAS objects processed?

I could always script out my processing tasks using SSMS and drop them in a SQL Agent job step.  But I have multiple environments and multiple cubes so each one would have to be hard coded.  Not a great idea, so scratch that.

Click through to learn the best way to fix this.

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SSAS Query Analyzer

Published 2018-02-20 by Kevin Feasel

Chris Webb reviews Analysis Services Query Analyzer:

Last week a new, free tool for analysing the performance of MDX queries on SSAS Multidimensional was released: Analysis Services Query Analyzer. You can get all the details and download it here:

https://ssasqueryanalyzer.github.io/

…and here’s a post on LinkedIn by one of the authors, Francesco De Chirico, explaining why he decided to build it:

https://www.linkedin.com/pulse/asqa-10-released-francesco-de-chirico/

I’ve played around with it a bit and I’m very impressed – it’s a really sophisticated and powerful tool, and one I’m going to spend some time learning because I’m sure it will be very useful to me.

Read on for the rest of Chris’s review, including product screenshots.

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Roll Your Own SSAS Performance Monitoring Tool

Published 2017-11-27 by Kevin Feasel

Shabnam Watson has a great post on building an Analysis Services performance monitoring tool from scratch using Power BI:

In many cases, SSAS works efficiently with default settings right out of the box. However, when you have large databases, substantial number of concurrent users, insufficient resources on your server, or when best practices are not followed during SSAS database design, you can run into performance bottlenecks and problems. In these scenarios, you need to know what to measure and how to measure them, what’s normal for your environment (benchmark), and you need to have some amount of historical measurements to be able to see the events that lead to a certain bad performance/failure point. Once you have this data, you can improve your server’s performance by addressing the problem(s).

This is a tour de force of an article, absolutely worth reading if you plan on dealing with Analysis Services at some point.  Even if you don’t build your own tool, you’ll learn a lot about what drives SSAS performance and what indicates that there might be a problem.

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BI Announcements At PASS Summit

Published 2017-11-03 by Kevin Feasel

Chris Webb points out some good news released at PASS Summit:

Power BI Report Server

There’s a new release of Power BI Report Server available, and you can read all about it here:

https://powerbi.microsoft.com/en-us/blog/new-version-of-power-bi-report-server-now-available/

The blog post highlights the fact that you can connect to SSRS shared datasets via OData – which is basically what I was talking about here.

This is the big one for me, but there are a few other product updates that Chris covers as well.

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Locale Problems With SSAS

Published 2017-11-01 by Kevin Feasel

Koen Verbeeck diagnoses an awful Analysis Services error:

This really didn’t make any sense. However, in one of the Discover Begin/End events, the same number appeared again: 8192 (this time explicitly marked as locale identifier). Hmmm, I had problems with weird locales before. I dug into my system, and yes, the English (Belgium) locale was lingering around. I removed it from my system and lo and behold, I could log into SSAS with SSMS again. Morale of the story: if you get weird errors, make sure you have a normal locale on your machine because apparently the SQL Server client tools go bonkers.

Worth reading the whole thing.  And also maybe just using en-US for all locales; at least that one gets tested…

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No Hierarchies In SSAS DirectQuery

Published 2017-10-06 by Kevin Feasel

Thomas LeBlanc points out that Analysis Services Tabular’s DirectQuery functionality does not include hierarchies on dimensions:

You can go to this like from Microsoft about more limitations.

There was also difference in labeling when designing a Tabular Model in Visual Studio (SQL Server Data Tools – SSDT) and making a change to the Model from SQL Server Management Studio – SSMS.

In SSDT, The Property for the Model is DirectQuery and the values are On and Off.

It’s certainly not the end of the world, but I can see it being a bit annoying to deal with.

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What’s New In Analysis Services

Published 2017-10-03 by Kevin Feasel

Christian Wade explains what’s new in SQL Server Analysis Services 2017:

SSAS 2017 introduces the 1400 compatibility level. Here are just some highlights of the new features:

  • New infrastructure for data connectivity and ingestion into tabular models with support for TOM APIs and TMSL scripting. This enables support for a range of additional data sources, and data transformation and mashup capabilities.

  • Support for BI tools such as Microsoft Excel enables drill-down to detailed data from an aggregated report. For example, when end-users view total sales for a region and month, they can view the associated order details.

  • Object-level security to secure table and column names in addition to the data within them.

  • Enhanced support for ragged hierarchies such as organizational charts and chart of accounts.

  • Various other improvements for performance, monitoring, and consistency with the Power BI modeling experience.

There’s plenty more where that came from (unless you’re a Multidimensional fan…), so click through for the details.

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