DirectQuery vs Vertipaq Modes in SSAS Tabular Model

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Darren McDowell
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1 DirectQuery vs Vertipaq Modes in SSAS Tabular Model Julie Koesmarno MCITP Database Administrator 2008 MCITP Database Developer 2008 MCITP Business Intelligence Developer 2008

2 Agenda Terminology DirectQuery vs In-Memory Hybrid Mode PASS DW/BI VC 2

3 Abstract The new and flashy Tabular Model for Analysis Services has been highly pitched with the in-memory (VertiPaq) capability allowing for complex queries to run very fast. This session with some live demo will uncover: Advantages and disadvantages of using in-memory cache to store and query data Restrictions on DirectQuery tabular model Hybrid mode utilization Impersonation and Partitioning techniques Prerequisite: Familiarity with basic Tabular Model project creation will be useful, but not mandatory PASS DW/BI VC 3

4 Tabular Model Architecture and Solution Terminology

5 Vertipaq DirectQuery In-Memory Cached xvelocity PASS DW/BI VC 5

6 Tabular Model Architecture Third Party Application Excel Reporting Services Power View Tabular Model DirectQuery In-Memory SQL Server Databases Non SQL Server Databases Files OData Cloud Services PASS DW/BI VC 6

7 Tabular Model Solutions Authoring (SSDT) Deployment Option Database Properties Connectivity PASS DW/BI VC 7

8 DirectQuery vs In-Memory Execution

9 Querying DAX DirectQuery DAX / MDX In-Memory Data Access Query Data Sources SQL VertiPaq SE Process PASS DW/BI VC 9

10 DirectQuery Security Query DirectQuery SQL Role DirectQuery Impersonation Impersonate Current User Default (Data Source login) Data Source Impersonation Windows User Service Account PASS DW/BI VC 10

11 In-Memory Security Query In-Memory Role Row Level Security VertiPaq SE Data Source Impersonation Process PASS DW/BI VC 11

12 DirectQuery vs In-Memory Design

13 Formula Compatibility Semantic differences xvelocity in-memory analytics engine (VertiPaq) SQL Server No Calculated Column in DirectQuery PASS DW/BI VC 13

14 DAX Functions Some DAX Functions are not supported in DirectQuery: No equivalent calculations in relational engine No equivalent SQL expressions Performance of converted expressions E.g. TOTALYTD, SAMEPERIODLASTYEAR More information on BOL: PASS DW/BI VC 14

15 DirectQuery vs In-Memory Administration

16 Processing Options (In-Memory) Mode Database Table Partition Process Default Process Full Process Data Process Clear Process Defrag Process Add Process Recalc Further reading: PASS DW/BI VC 16

technology on SQL Server 2012 Partitioning / ColumnStore

17 Partitioning in DirectQuery One partition in Tabular Model Can take advantage of Partitioning and ColumnStore Index technology on SQL Server 2012 Partitioning / ColumnStore management done at the source database level PASS DW/BI VC 17

18 Partitioning in In-Memory In-Memory can have multiple mutually exclusive partitions To eliminate unnecessary processing and processor load on the AS servers C u r r e n t Mar 2012 Process Feb 2012 Jan 2012 In-Memory Partitions PASS DW/BI VC 18

19 DirectQuery vs In-Memory Pros and Cons

20 In-Memory - Pros ALL functionality of Tabular Model Calculated Columns, ALL DAX functions Row Level security xvelocity in-memory analytics engine Many choices of client tool Excel, Power View, SSRS, MDX client* Many supported data sources PASS DW/BI VC 20

21 In-Memory - Cons AS requires Memory & CPU resources Caching Processing Querying Diligent Partitioning and Processing Out of date data PASS DW/BI VC 21

22 DirectQuery - Pros Real time access Scalable SQL Server permission SQL Server optimisation Consistency One Partition to manage No processing required PASS DW/BI VC 22

23 DirectQuery - Cons Restricted DAX functions Restricted client tools: PowerView, SSRS No Row Level Security Unless defined at the source Database No Calculated Columns PASS DW/BI VC 23

24 The best of both worlds Hybrid Mode

25 Tabular Model Solutions DirectQueryMode On Off Query Mode DirectQuery DirectQuery with In-Memory In-Memory with DirectQuery In-Memory Connection String: DirectQueryMode=DirectQuery DirectQueryMode=In-Memory PASS DW/BI VC 25

26 Partitioning for Hybrid Mode One Partition for DirectQuery Processing Option: Never process this partition Multiple Partitions for In-Memory (No Overlap) C u r r e n t Mar 2012 DirectQuery Partition Feb 2012 Jan 2012 In-Memory Partitions PASS DW/BI VC 26

27 Implications Inconsistency Data stale data in Cache Calculations semantic differences xvelocity vs SQL Security DirectQuery Design Flexibility at run time / client tools In-Memory (Excel) or DirectQuery (Real time) PASS DW/BI VC 27

28 Wrap Up

29 Tabular Model Modes In-Memory Mode (default) DirectQuery Mode DirectQuery only DirectQuery with In-Memory In-Memory with DirectQuery PASS DW/BI VC 29

30 Do I DirectQuery? SQL Server database is optimised Columnstore Index Partitioning Contains required most business rules High Volume Can import non-sql data into one SQL Server database which will be the source PASS DW/BI VC 30

31 Further Reading Cathy Dumas blog aspx SQLBI (Marco Russo & Alberto Ferrari) DAX resources (with links to Tabular Model) PASS DW/BI VC 31

32 Q & A signal@mssqlgirl.com PASS DW/BI VC 32

33 Thank you!

Toolkit for DAX Optimization

Toolkit for DAX Optimization Marco Russo marco@sqlbi.com SQL Saturday #464, Melbourne 20 th February 2016 Housekeeping Mobile Phones please set to stun during sessions Evaluations complete online to be