Transcript SSAS 2012 Tabular Mode Best Practices Itay Braun CTO & BI Architect, Twingo Manager of the Microsoft BI User Group in Israel [email protected].

SSAS 2012 Tabular Mode
Best Practices
Itay Braun
CTO & BI Architect, Twingo
Manager of the Microsoft BI User Group in
Israel
[email protected]
Target
• Understanding what is exactly SSAS 2012
Tabular Mode and when to use it
• Understanding the “small letters “
Exact Limitations
PowerView
• Great Visualization functionality
• Simple and intuitive
•
•
•
BTW,
Part of SharePoint 2010 Enterprise Edition
Can only query SSAS 2012 Tabular Model
PowerView
• Great Visualization functionality
• Simple and intuitive
BTW,
– Part SharePoint 2010 Enterprise Edition
– Can only query SSAS 2012 Tabular Model
Agenda
• General BI Solution Architecture
• What is SSAS 2012 Tabular Mode
–
–
–
–
–
–
BISM and other Main Features
Direct Query
DAX vs. MDX
Processing
Security
Clients
• PoC – Lessons Learned
BI Solution Architecture
BI Solution Requirements
• Business Requirements:
•
•
•
•
•
single version of the truth
unified data
KPI and CPM
Dashboards
Reports…
• Technology is just an Enabler
• Main Technological Requirements:
–
–
–
–
–
Easy to change and maintain
Security
Good performances
Self Service BI
Good visualization layer
Using a New Technology
• What does it do?
• When should I use it?
– And when shouldn’t I use it?
• What’s it place in the technological road map?
– Two examples
• Similar Technologies
– Who are the biggest competitors?
– Which old technology replaced by the new one?
SSAS 2012 Tabular Mode
• Customers ask:
– Does it replace good old MOLAP or is it just a better
PowerPivot?
– From now on, should I develop in Tabular Mode only?
– We understand that in-memory column database is
faster. How fast is Tabular compared to MOLAP?
– We understand that development at Tabular Mode is
simpler. We are SSAS 2008 R2 experts and know
nothing about DAX and Tabular. Would you still say
Tabular is simpler option for us?
Is SSAS 2012 Tabular Mode Enterprise Ready?
WHAT IS SSAS 2012 TABULAR MODE?
What is SSAS 2012 Tabular Mode
• New DB Engine
• Tabular Mode
–
–
–
–
Column Store
In-Memory
Compression (about 1:3; sometimes much better)
All data copied (processed) to the Tabular model
• Direct SQL
– Queries translated to SQL, running directly against
the relational SQL Server.
– Tabular Mode’s version of ROLAP
BISM – BI Semantic Model
• BISM is a concept, not a technical term
• Users can easily query the intuitive data model
– No need to understand complex data source structure
• The BISM provides:
– Data Model
– Business Logic and Queries
– Data Access
• The implementation of the BISM are these three technologies:
• MOLAP
• SSAS Tabular Mode
• PowerPivot
Tabular vs. Multi Dimensional
• Tabular
–
–
–
–
Quicker development
From detailed (granular, images) data to aggregate data
Good performances
Some features are missing
• Multi-Dimensional
– Rich Multi-dimensional functionality
– Known and well documented engine
– Suitable for very large cubes, beyond server’s memory
size
Schema (SQL Server Data Tools)
Management Studio
Tabular Mode - Main Features
• Understanding the main features of a technology
is the key to understand when and how to use it
– Feature by Server Mode or Solution Type
Developing a Model
• Use the Visual Studio SQL Server Data Tools to
build a BISM
• Open an existing PowerPivot Model using SSDT
or Management Studio
• Deployment
– Immediate changes implementation
at the SDDT
– Use small DB for development
Workspace Database
• Created during model authoring using SSDT.
• Disappeared automatically when closing the
project
• The workspace database resides in-memory.
Workspace DB
Data Sources
• The model can use multiple data sources
Tabular Mode Schema vs. Data Source Views
• Much simpler than a Data Source View
• Building the AdventureWorks DB using Tabular
Mode is about x4 times faster.
Tabular Mode Schema
• Dimension = One Table
• No Dimension Wizard to create Hierarchies
Tabular Mode Schema
• Measures and KPI are defined here.
No cube Wizard.
Tabular Mode Schema
• Edit Table Properties
Tabular Mode Schema- Adding a column
• Adding new calculated columns in the schema is
possible.
• Either add calculated columns to the source DB
or to the BISM
Adding a new columns
• Add new columns using DAX
– At the OLAP Data Source View you write an
expression in the source language, TSQL, PLSQL…
Schema - Limitations
• Self Joins are not supported
• Two tables can have only one active
relationships
– No role playing dimension
• Many to Many relationships allowed using DAX
Dimensions
• Active / non active relationships
– Only ONE relationship can be active
– No Role Playing Dimensions
– The Date Dimension can be connected by
either OrderDate or ShipDate or DueDate
You’ll have to build many date dimensions
Dimensions
• Dimensions
• Multiple Hierarchies
Snowflake Dimensions
• A dimension is based on one table / view only.
– A hierarchy can be based on one Table.
– Create a view on the data source which joins the
tables.
• .
Category name from Dim Category with a measure works
as expected
Dimensions - Limitations
•
•
•
•
•
No member properties
No Parent-Child
No linked dimensions
No need for Attribute Relationships
The dimension is a table
– A dimension can be based on one and only one table
– Dimension names taken directly from the
• Large dimensions (million members ) performed
better
Measures
• Sum, min, max, count, distinct count…or
complex DAX Expressions
• A table can contain both attributes and
measures.
Multi Grain Measure Groups
• Support many “Measure Groups” with different
dimensionality
• For ex. Internet Sales (product level), Sales
Quota (Category Level)
KPI
• Key performance Indicators are the heart of
any BI solution
• Replaces existing Measures
KPI
• Easy to create using a wizard
• Value – existing measure
• Target – measure or a number
• Status – using a GUI
Perspectives
• Same as in SSAS Multidimensional
• Allows users to see a Database in a simpler way
• Can hide:
–
–
–
–
–
Tables (dimensions)
Columns (Attributes)
Hierarchies
Measures
KPI
Partitions
• Same logic as in SSAS Multidimensional.
• Easy to create
• Can be processed alone (like in
Multidimensional)
What’s missing?
•
•
•
•
•
•
Translations
Sync Two Databases
Actions
Custom Assemblies (SSAS Procedures)
Self Join (Parent Child)
Role Playing Dimensions
More Limitations
• Named Set
• Scopes
• Write Back
Direct Query
DirectQuery Mode
• DirectQuery mode uses data that is stored in a
SQL Server database.
• Used for Real Time analysis
• No processing
– Changes to the underlying source data reflected
immediately.
– no extra management overhead of having to maintain
a separate copy of the data.
Direct Query
• Performances
– No clear answer, depends on the source DB
– Still checking the efficiency of the generated SQL
Queries.
• Security - Any security enforced by the back-end
database is guaranteed to be enforced, using
row-level security
• Unlike Multi Dimensional, you Can’t mix Direct
Query and Tabular Partitions
Direct Query Limitations
• Can only use one SQL Server DB as a source
• The entire model is either is either using
DirectQuery or not.
• Limited use of DAX functions
• Client restrictions: Can only be queried by using
DAX
– Excel can’t be
used because it
uses MDX
DAX vs. MDX
DAX vs. MDX
• MDX (Multi Dimensional Cube) vs. DAX
• MDX (Tabular) vs. DAX (Tabular)
Querying a Tabular Model using MDX
• Quick start – just use MDX to query the model
– You don’t have to learn DAX
– In general speaking, MDW performs well
– Fine tuning DAX queries
What is DAX
• Set of Excel-like formulas
• Enables advanced data modeling inside the
PowerPivot for Excel or Tabular Mode
• Two types of calculations
– calculated columns
– measures
Learn DAX
• QuickStart: Learn DAX Basics in 30 Minutes
• http://www.sqlbi.com/
• Chris Webb’s blog. 6 lessons about DAX start
here
• Converting MDX to DAX – First Steps
DAX vs. MDX
• DAX and MDX coexists peacefully
• Tabular Mode can be queried using both DAX
and MDX
• Use MDX for data analysis (group by,
hierarchies)
• Use DAX for detailed reports
– MDX uses Crossjoin to join many columns.
- Excel uses MDX, PowerView uses DAX, SSRS
can use both
DAX vs. MDX
• More Limitations
– MDX can only query In-Memory Models
– DAX can query both In-Memory and Direct Query
Models.
– DAX cannot be used to query Multi Dimensional
Cubes
• Microsoft are working on it
(Tabular + DAX) vs. (MOLAP + MDX)
• The fact that VertiPaq is an in-memory
database doesn't mean that it will perform much
better than a multidimensional cube.
• Warm Cache MOLAP Cube query will probably
perform better or just as good as DAX.
– Query results caching
(Tabular + DAX) vs. (MOLAP + MDX)
• DAX on Tabular mode usually give you good
performance without special tuning.
• DAX queries are never cached
– Second (warm) run is just as fast the first (cold) one.
• Distinct Count queries usually performed better
using DAX + Tabular
– Overall good performance of DC even with MDX
When number of days increased – the runtime of MDX(CUBE)
query is better then DAX (Tabular)
Complex query that run on list of members (Products and Dates) and
make aggregations – will return faster in MDX (Cube)
(and much faster from the warm cache) than in DAX.
MDX Query
Same Query in DAX
DAX in XMLA
• Easy to manage parameters
• DAX Editor sample
Processing
Processing Highlights
•
•
•
•
Tables can be partitioned
Process FULL
Process ADD (incremental)
One table (dimension) can be processed
without processing the related measures
Processing
Processing Error
It says “processed” but the
error message and a closer
look on the partitions shows
the table has never been
processed
Processing
• Process the dimensions
• Process the measures
• Unlike MOLAP, It is possible to query tables
(dimensions and measures ) while other tables
haven’t been processed yet.
Processing the
dimensions but not
the measure tables
Partitions
Partitions
• Every table can be partitioned.
• Since Dimension = Table, a dimension can be
partitioned too.
– Not sure this is a good idea.
Partitions
• It is possible to process only some of the
partitions
Process Full
• Processes a partition or table and all the objects
that it contains.
• Drops all data, and then processes the object.
– Any affected calculated columns, relationships, user
hierarchies, or internal engine structures (except table
dictionaries) are recalculated.
• This kind of processing is required when a
structural change has been made to an object.
Processing Options
• Process Clear - Drops all the data in a database,
table, or partition.
• Process Data - Loads data into a partition or
table.
• Process Defrag - Optimizes the table dictionary
(an internal engine structure)
– For ex. After deleting old partition, the dictionary still
contains references to these deleted rows.
– The best practice is to run it frequently, based on your
sliding window design
Processing Options
• Process Recalc - recalculates calculated
columns, rebuilds relationships, rebuilds user
hierarchies and rebuilds other internal engine
structures.
– Must be issued after Process Clear or Process Data.
Handling Unknown Values
• A dimension key in the Fact table might be
missing in the dimension table.
– For ex. A sale of 2024.99$ for a non-existing product
• It is not possible to configure the processing
behaviour.
• All unknown rows merged into one “unknown’
member
Using Views in the Tabular Model
• Use views to filter small amount of data at the
development phase, later change the view
definition to return all data.
• Using views let you do changes in the
underlying DB without affecting the Tabular
Model Schema.
ProcessAdd
• The simplest solution – add a new partition +
Full processing
• It is possible to run process add to load new
data.
• It is under the responsibility of the DBA to avoid
duplication.
• You can change the query binding using the UI.
– Use views as much simpler query binding.
Parallel Processing
• It is possible to process many tables on parallel.
• However, only one partition of a table at a time.
Security
Security
• Two main permissions:
– Database Permissions
– Allowed Row Sets
• Create roles using SSDT.
• Use DAX to restrict access
–
=Region[Country]=”USA”
• Dynamic security is also possible
– http://msdn.microsoft.com/enus/library/hh213165(v=sql.110).aspx
Security
• Create a role
Add the role name to the
connection string
Always
uses Visual
Total
View filtered data
PoC – Lessons Learned
PoC – Lessons Learned
• Forget what you know about SSAS 2008, new
design is needed
– No Migration Wizard
– Consider de-normalization.
• Server Configuration
– Server Properties (SSAS - Tabular)
– Memory paging allows models to be larger than the
physical memory of the server
Clients
PowerView
• A feature of SQL Server 2012 Reporting
Services Add-in
– Requires Microsoft SharePoint Server 2010
Enterprise Edition
• Interactive data exploration and visualization
• Intuitive ad-hoc reporting for business users
• A browser-based Silverlight application
Clients - PowerView
• For only SSAS 2012 Tabular Mode or
PowerPivot.
– SSAS 2012 Multi-dimensional as data source is
planned for the near future.
• Watch demo here
• More info at MSDN
Clients – Pyramid Analytics
• The Pyramid Analytics Suite is a highly scalable,
enterprise data analytics application that brings
sophistication with simplicity in a synergistic
web-based interface for consuming Microsoft
Analysis Services OLAP cubes.
• BioPoint Dashboards
• BioXL - A complete browser-based cube viewing
solution
Clients – Excel 2010
Clients - Custom
• Build your own app using AMO
Monitoring
• Good monitoring is essential for Enterprise
Ready solutions.
–
–
–
–
Profiler
Dynamic Management Views
Performance Monitor
No query log, though
Licensing
• Tabular Mode not in Standard Edition
Conclusion
• Multi Dimensional OLAP:
– Familiar, Huge Install base, wide knowledgebase,
stable, large scale implementations, monitoring tools,
many OLAP Viewers
• Tabular Mode
– New Technology
– Simple, easier development, sometimes faster
– Microsoft now focusing on this technology
Links
• My Blog:
http://blogs.microsoft.co.il/blogs/itaybraun
• Cathy dumas’ blog: http://cathydumas.com/
• DAX Editor - http://daxeditor.codeplex.com/
• Paul Te Braak’s blog
• AdventureWorks tutorial for tabular models
• DAX quick start guide
Thanks