We have VS 2019 for SSAS development (with installed SSDT).
I would like to create aggregations for measures in order to increase query performance (cube with tabular model).
Could you tell, please, where the window "Aggregation" is located in VS?
P.S. on the screen you can see a snapshot from the video on youtube where i highlighted the ribbon (and button) i am searching for.
From the screenshot, it looks like, You are looking into a video on SSAS (multi dimensional). It is having aggregations. For SSAS (Tabular), there are no custom aggregations.
You can see the difference between SSAS (multidimensional) Vs SSAS (Tabular) here
Feature
Multidimensional
Tabular
Aggregations
Yes
No
Related
I hope you are doing well.
I'm working on a migration from an on premise ssas multidimensionnal cube to an azure analysis services tabular model.
Is there a way , a method or a tool to do it quickly and efficiently?
It's a large cube and it will take time to develop it from scratch with tabular model.
Thank you for your help
SSAS Multi Dimensional (MD) and Tabular are fundamentally different technologies, there is no quick method of converting one to the other, you will have to rebuild the model from scratch, and the measures etc.
Be aware that some of the things MD models are good at, like calculating up and down hierarchies, Tabular really struggles with. If the cube is fundamentally sound and has good performance, and you want to move it into the cloud service, use a VM in Azure, with SQL Server on it, it may work out cheaper that Azure AS, per month.
I'm having a real hard time understanding what the difference is between a tabular vs multidimensional model.
Don't both use dimensions and fact tables?
Can't both have a star or snowflake schema?
Don't both have measures and calculated columns?
What is the difference?
Also, if I'm using Power BI and I connect to SQL Server instead of SSAS, I can still do my thing with it. Why is SSAS needed for tabular models if you can just do it in SQL Server?
Don't both use dimensions and fact tables?
Nope. Multidimensional uses Attribute Hierarchies and Measure Groups. Tabular uses Tables, and has no built-in notion of what a "fact" or "dimension" is.
Can't both have a star or snowflake schema?
Yes. And Tabular can have other designs as well. Tabular models can have single-table, or more normalized schemas, although using a star or snowflake design is generally considered a best-practice.
Don't both have measures and calculated columns?
MD does not have calculated columns. See Comparing tabular and multidimensional solutions
Also, if I'm using Power BI and I connect to SQL Server instead of SSAS, I can still do my thing with it.
Nope. Power BI always uses a Tabular or Multi-Dimensional model. When you connect to SQL Server with Power BI you are creating a Tabular model, and either Importing the data into memory, or creating a DirectQuery model (or a hybrid). In either case there is still a Tabular Model created, either embedded in the .PBIX or in a SSAS/AAS server.
I've working on SSAS cube creation first time on real data(Although had little hands on experience on AdventureWorksDW08).I also have gone through the details for creating basics cube and all but have little question as to which are the pre-requisite for creating the SSAS cube .e.g (SQL TABLE SHOULD NOT HAVE NULL VALUES) etc.
I'm Tried so many times but it seems that data is not get refresh for certain result columns.
I am using PowerBI desktop and connecting to a SSAS tabular model cube. This is working just fine, except there are three measures missing from the list of fields.
Through experimentation, I was able to determine that any measure with a MEDIAN or MEDIANX function is not being brought into PowerBI. If I use SUM, the measure will appear. I made sure to check for hidden measures but anything with those MEDIAN functions are nowhere to be found.
These are simple measures, similar to:
Median of X:=MEDIAN([X])
It would appear PowerBI is filtering out Medians on purpose, but I can't figure out why. I suppose I could make my own Median measure in the PowerBI desktop, but my clients want to be able to easily grab the measure from the cube... which kind of makes sense because that's why we built the cube in the first place, right?
Any ideas on how to fix this? Any help will be greatly appreciated.
UPDATE:
I have tried adding the measure three different ways:
Median Measure1:=MEDIAN([Column])
Median Measure2:=MEDIAN(Table[Column])
Median MeasureX:=MEDIANX(Table, [Column])
All three appear in the measures when I load the data source to a PivotTable. They all work identical.
I also connected to this data source in SSRS Report Builder and I am able to see all three measures.
I then connect to the datasource live in PowerBI Desktop. The measures are nowhere to be found. I can search for "median" and I receive no results. If I view hidden fields, they are still nowhere to be found.
I am using the following PowerBI Desktop version:
2.50.4859.502 64-bit (September 2017)
I will also add that I have other aggregate measures using the same table/column that are appearing fine in Power BI.
Our SSAS Tabular models are using SQL Server 2012 RTM (1100) compatibility level. Would this affect the measure in PowerBI?
This question was posted to the PowerBI forums and I will update this question if I get an answer on there.
I was wondering if anyone here knows the exact differences for these 2 modes, more specifically:
What can we do in one model that we can't do with the other? (Multi-dimensional vs Tabular and vice versa)
How is the data stored in one model versus another?
If I am wring an SSRS / PowerBI / Excel report against this, what limitations does one model have over the other?
Does the tabular model have cubes? If not, what is the alternative storage medium and how does it differ from cubes (maybe provide for me
some background on what cubes are to begin with)
What are the differences in security considerations? As I understand, with the Multi-dimensional model, row-level, column, level
and even cell-level security can be applied - what is available with
this for the tabular model?
Also, as I understand SQL Server 2016 is moving to using the Tabular Model by default and that there may be some differences/improvements
over what is current in use (SQL Server 2014) - can you please provide
a list of what those are?
Thank you so much in advance.
A good place to start might be these articles which should be accurate as to the differences in SSAS 2014.
Advice on the decision points for choosing to build a Tabular or Multidimensional model
Paul Turley’s high-level description of Tabular strengths and weaknesses
Dimension relationships
Summary level presentation
Many-to-many relationships and writeback and scope statements and non-visual dimension security are some of the biggest missing features in SSAS 2014 Tabular in my opinion.
Tabular security is row based and just supports visual totals, not non-visual totals or cell security. But in many cases you don't want to use cell security for performance reasons.
Tabular uses in-memory columnar storage. Multidimensional uses disk-based row-based storage. So scanning a billion row fact table requires reading all columns from disk in Multidimensional and takes a minute or two to return a query on a fact table that large. If you optimize the Multidimensional model by building an aggregation then the query may take seconds. Tabular just scans the columns used in the query and simple queries or calculations even on a billion row table may return in under a second.
With SSAS 2016 Tabular the bidirectional relationship was added which was a very big deal for modeling flexibility and allowing many-to-many relationships. And parallel partition processing made loading large models feasible.
SQL 2017 installer for SSAS has Tabular as the default.
If you have the option for using SSAS 2016 Tabular or above it is highly recommended for performance and modeling flexibility. Here is what's new in SSAS 2016 and SSAS 2017.