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Category: Analysis Services

SSAS and Database Loading

Nigel Foulkes-Nock explains why SSAS might not be available even if the service is running:

When starting SQL Server Analysis Services (SSAS) Tabular, the Service is quick to report that it has started. In my opinion, this Status is not entirely accurate – SSAS may be running but you cannot access data until it has loaded all associated SSAS Databases into memory and performed its consistency checks. This can take a long time.

After starting SSAS, if you try to browse the Databases using SQL Server Management Studio (SSMS) then SSMS becomes unresponsive. You will receive errors if you try to query a SSAS Database. It’s busy but it doesn’t report as such and doesn’t give any clue of how long it’ll take.

Read on for the explanation.

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Visualizing Analysis Services Tasks with the Job Graph

Chris Webb is excited:

More details about it, and how it can be used, are in the samples here:

https://github.com/microsoft/Analysis-Services/tree/master/ASJobGraphEvents

The data returned by the Job Graph event isn’t intelligible if you look at the text it returns in Profiler. However if you save a .trc file with Job Graph event data to XML you can use the Python scripts in the GitHub repo to generate DGML diagrams that can be viewed in Visual Studio, plus Gantt charts embedded in HTML. Of course to do this you’ll need to have Python installed; you’ll also need to have Visual Studio and its DGML editor installed (see here for details).

Read on to see how it looks and Chris’s thoughts on the matter.

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SSAS Performance Counters to Monitor

Steven Wright takes us through a set of SQL Server Analysis Services performance counters we should track:

That said, I wanted to provide some updates with more of a focus on Tabular mode, as it has clearly become the new standard for how most organizations deploy SSAS. I recommend referring to that original series for a focus on Multidimensional mode, but much of the information provided in this blog post will be applicable to both modes. I recommend referencing Allen White’s blog post on SQL Server counters to learn more about many of the Windows-level counters that apply across the board, as I won’t speak to them here.

Let’s dive into the 15 SSAS performance counters you should be monitoring.

Click through for the set, as well as explanations for why.

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Calculation Groups with Disconnected Tables in Power BI

Gilbert Quevauvilliers shows how to build a calculation group based on a disconnected table in Power BI and Azure Analysis Services:

I know that some of this might be able to be done with other calculation groups. I find I have more flexibility when combining Calculation Groups with a disconnected table.

Below are some of my previous calculation group blog posts that might also be of interest:

Create Currency Formatting Strings using Calculation Groups in Power BI Pro & Premium / Azure Analysis Services / SQL Server Analysis Services 2019

How to create and use Calculation Groups in Power BI Pro & Premium / Azure Analysis Services / SQL Server Analysis Services 2019

Click through for the demo.

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Killing Idle Analysis Services Sessions

Shabnam Watson shows us how to kill idle SQL Server Analysis Services sessions:

Think of this method as an emergency procedure only. As always, have database backups and try this on a development server first. Always take a backup of msmdsrv.ini before you modify any server properties. The default location of the file is this: C:\Program Files\Microsoft SQL Server\MSAS15.MSSQLSERVER\OLAP\Config

If you set the timeout values too low on server that is under resource pressure, you may not be able to get to the server properties using SSMS and change them quickly within the time you set for the timeout. For this reason, I prefer the user of XMLA in this case which makes the process faster.

Read on to see how to do this.

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Parallel Processing in Analysis Services

Kasper de Jonge takes us through parallel processing of partitions and tables in Analysis Services:

One thing that has come up several times in the last few weeks is a misconception that you cannot process multiple partitions on the same table or tables in parallel as it would cause a lock. This could be true if you try to do the parallelism yourself. Like in SQL Server you need to think about transactions, the AS engine is a transactional system too.

So, the AS engine is definitely capable of loading data in parallel but only if you let him do the puzzling on concurrency. This means you must send processing commands to the AS engine in one transaction so the AS engine can manage the locks itself. There are other benefits of letting AS doing the work like recalculating the calculated items (tables, columns etc) once instead of multiple times which improves processing performance.

Read on for an example.

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Creating Currency Formatting Strings with Power BI

Gilbert Quevauvilliers walks us through formatting currencies via calculation groups in Power BI and Analysis services:

When I first started looking at the calculation groups and changing the currency formats, I thought that my existing currency format was correct. Boy was I wrong and once I found that out and corrected it, my Currency Format Strings started working.

As per the Microsoft documentation found here Dynamic format strings for currency conversion I had to make sure that my Currency format followed the following pattern.

Read on for an example and demonstration.

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Calculation Groups in Analysis Services and Power BI

Kasper de Jonge walks us through calculation groups:

In most cases the business wants to see some common calculations done over these measures like YTD, QTD, YoY% etc. That means you must make a new measure for each of the calculation over the base measure. This leads to measure explosion in your model as you need to add a new measure for each variation. Very quickly this leads to not four measures but sixteen and more creating a management headache.

In come calculation groups. With calculation groups you can create a group that can apply common calculation over base measures. It’s hard to explain so let’s just dive in on how that works.

Click through for a demo of how to enable and use calculation groups.

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Power BI Warning Regarding “Store datasets in enhanced metadata format”

Imke Feldmann does not recommend turning on the “Store datasets in enhanced metadata format” setting in Power BI all willy-nilly:

Background

With the march release came function “Store datasets in enhanced metadata format”. With this feature turned on, Power BI data models will be stored in the same format than Analysis Services Tabular models. This means that they inherit the same amazing options, that this open-platform connectivity enables.

Limitations and their consequences

But with the current setup, you could end up with a non-working file which you would have to build up from scratch for many parts. So make sure to fully read the documentation . Now!

Read on to see what has Imke concerned.

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Approximate Distinct Count with DAX

Gilbert Quevauvilliers runs some performance tests against the approximate distinct count formula in DAX:

I am currently running SQL Server Analysis Services (SSAS) 2019 Enterprise Edition. (This can also be applied to Power BI)

My Fact table has got roughly 950 Million rows stored in

And as mentioned previously it has got over 64 Million distinct users.

The data is queried from SQL Server into SSAS.

Gilbert first checks how close these are and then how much faster the approximate count is.

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