Storing Constants For MDX Calculated Measures

Chris Webb walks us through an interesting performance problem when using Analysis Services multidimensional:

All it does is take the value of the Sales Amount measure at the lowest granularities of the Customer, Date and Product dimensions, multiply it by 0.08 to find a tax value, and because [Tax Amount] is a real, non-calculated measure, the result of the calculation aggregates up through the cube. [I know that I don’t have to aggregate the result of this specific calculation but remember that this is a simplified example – in the real case I did have to write the calculation using Scope statements – and anyway the best way of handling a basic multiplication like this would be with a measure expression]

The performance was sub-second for my test query and I was happy, but then I realised that the same tax rate was being used in other calculations and may change in the future, so I thought I would store the value 0.08 in a calculated measure:

Chris walks through several iterations of this before landing on a solution which is both reasonable and fast.

Clearing The SSAS Cache Using C#

Shabnam Watson shows us a small console program to clear the SQL Server Analysis Services cache:

First let me give you a little background of why you would want to clear SSAS cache from C# code when you can do this using an XMLA command from SSMS.

If you have a slow MDX/DAX SSAS query , you have a couple of options for improving the performance (assuming no hardware changes):

  1. Rewrite the query differently if you have control over the query. (You will have two queries that you want to compare against the same database.)
  2. Make changes to the SSAS database to follow a better design. (You will have one query to run against two databases)

Regardless of which route you go, you should compare the performance before and after the changes to see how much you gained from the change.

Click through for more, including the code.

Changing Connection Strings In VertiPaq Analyzer

Shabnam Watson shows us how to change the connection string in VertiPaq Analyzer, a plugin for Excel:

While trying to set up VertiPaq Analyzer on a new computer, I ran into a problem where Excel was not letting me change the SSAS connection that was built in the workbook. It turns out I had missed one of steps in the instructions in the workbook. As a result, when I got to Connection Properties, everything was grayed out and this message was at the bottom:

Some properties cannot be changed because this connection was modified using PowerPivot Add-in.

Read on to see how to fix this.  And check out VertiPaq Analyzer if you’re working heavily with Analysis Services Tabular or Power BI.

Power BI August Release And SSAS Performance Improvements

Chris Webb points out something new in the Power BI August 2018 release:

While I was playing around with the new release (August 2018) of Power BI Desktop I noticed there was an undocumented change: similar to the OData improvements I blogged about here, there is a new option in the AnalysisServices.Database() and AnalysisServices.Databases() M functions that turns on a newer version of the MDX generation layer used by the Power Query engine. Like the OData improvements it is an option called Implementation=”2.0”, used like this:

AnalysisServices.Databases(	"localhost",	[	TypedMeasureColumns=true,	Implementation="2.0"	]
)

…and also, as with the OData improvements, you will need to manually edit any existing M queries to take advantage of this.

Read on for Chris’s test and analysis of the resulting MDX output.

Testing BI Projects With NBi: Hierarchies And Levels

Cedric Charlier shows us a potential pain point when testing an Analysis Services cube with hierarchies defined:

When executing the following query (on the Adventure Works 2012 sample database/cube), you’ll see two columns in the result displayed by SSMS. It’s probably what you’re expecting, you’re only selecting one specific level of the hierarchy [Date].[Calendar Date] and one measure.

You’re probably expecting that NBi will also consider two columns. Unfortunately, it’s not the case: NBi will consider 4 columns! What are the additional and unexpected columns? The [Date].[Calendar].[Calendar Year] and [Date].[Calendar].[Calendar Semester] are also returned. In reality, this is not something specific to NBi, it’s just the standard behaviour of the ADOMD library and SSMS is cheating when only displaying one column for the level!

Click through for the solution.  And if NBi sounds interesting, check out Cedric’s prior post on the topic.

SSAS Tabular Deployment Fails: Newtonsoft.Json Missing

Alex Whittles walks us through an error deploying a SQL Server Analysis Services tabular model:

Deploying an Analysis Services Tabular model to SSAS Azure using the Analysis Services Deployment Wizard. Both Visual Studio 2017 & SQL Server 2017 installed on the client.

Try and click on the ellipses to change the data source connection string or impersonation information results in a Newtonsoft.json error:

“Could not load file or assembly ‘Newtonsoft.Json, Version 6.0.0.0, Culture=neutral, ……”

As I like to joke, every single .NET project in existence includes Newtonsoft.Json.  As Alex shows, sometimes they don’t reference the right version.

Scaling Azure Analysis Services

Chris Seferlis helps us make the decision between scaling up or out with Azure Analysis Services:

Some of you may not know when or how to scale up your queries or scale out your processing. Today I’d like to help with understanding when and how using Azure Analysis Services. First, you need to decide which tier you should be using. You can do that by looking at the QPUs (Query Processing Units) of each tier on Azure. Here’s a quick breakdown:

  • Developer Tier – gives you up to 20 QPUs

  • Basic Tier – is a mid-scale tier, not meant for heavy loads

  • Standard Tier (currently the highest available) – allows you more capability and flexibility

Read on for some pointers.

Figuring Out Azure Analysis Services Costs

Chris Webb explains that Azure Analysis Services might not be quite as expensive as you’d first think:

What does this mean for the cost of Azure Analysis Services? Basically, if you’re taking advantage of these features you won’t pay one of the monthly prices quoted on the pricing page linked to at the top of this post. Instead you may do things like:

  • Scale up for one hour every day when you need to process your SSAS database, just to get the extra memory and QPUs needed, then scale down when processing has finished
  • Scale out only on certain days, or certain times of day, to handle increased numbers of users
  • Pause your instance when you are sure that no-one needs to run queries

How do you then calculate the likely cost? For my Azure Analysis Services precon at SQLBits a few months ago I built an Excel workbook that shows how to go about this.

There are some good questions in the comments section, so check those out as well.

Deleting Analysis Services Tabular Partitions Using C#

Chris Koester shows how to delete SQL Server Analysis Services Tabular partitions using the .NET library:

This post shows how to delete SSAS Tabular partitions with C#. This is an improvement over a PowerShell script I previously wrote about, Delete SSAS Partitions with TMSL and PowerShell, because it is more dynamic and doesn’t require a manually-authored TMSL script.

Specifically, the code below deletes all partitions that contain a specified suffix, which is useful for quickly deleting all partitions used for development purposes. I’ve worked with SSAS models that required several development partitions in order to prevent the workspace database from growing too large. Deleting them manually after a deployment to a server would be tedious, and it would be easy to forget one and end up processing duplicate data.

Click through for the code.

Error Processing SSIS Task When TargetServerVersion Is SQL Server 2016

Shabnam Watson diagnoses an error condition when trying to run an Analysis Services processing task inside SQL Server Integration Services:

I ran into this problem a while ago at a client. They upgraded from Visual Studio 2013 to 2015 and the SSAS processing tasks started to error out immediately. The solution turned out to be setting the TargetSeverVersion to anything but SQL Server 2016. In this case, it was set to 2014 and that fixed the error.

Recently I ran into this post https://twitter.com/SQLKohai/status/994335086425399297 by Matt Cushing (@SQLKohai) and decided to dig in more.  Initially when I tested it, all was working fine. After I installed SSDT 2015 to test, I started getting the same error in SSDT 2017.  I played around with a DLL and got SSDT 2017 to work with all TargetVersionServers again. At the end I managed to break it again after I went through an uninstall and reinstall of all versions of SSDT. The reason I did the reinstall of SSDT was that I thought I might have had a broken registry entry that I was hoping the installation would fix. This did not work!

Read on for the solution and a detailed dive into the problem.

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