Shabnam Watson. SQL Server Analysis Services for DBAs

Transcription

1 Shabnam Watson SQL Server Analysis Services for DBAs

2 Shabnam Watson BI Consultant Work: BI Consultant Fifteen Years of experience developing data warehouse and business intelligence solutions with focus on SQL Server Analysis Services. Speaking PASS Summit, SQL Saturdays, Women In Technology Virtual Chapter and Atlanta SQL Server user groups. Background Master's degree in computer science and Certified Business Intelligence Professional (CBIP) by The Data Warehouse Institute (TDWI).

3 What s covered High level look at SSAS (MD and Tabular) Server side look at SSAS How SSAS interacts with SQL Server Best practices

4 What s NOT covered Data modeling Creating dimensions, cubes, MDX calculations. Creating Tabular models, DAX calculations.

5 Feedback

6 What is SQL Server Analysis Services

7 SSAS SQL Server SSAS Report Online Analytical Data engine (OLAP) Optimized for BI queries Usually is paired with SQL Server Semantic Layer: Predefined relationships Central repository of calculations

8 Multidimensional model MDX/DAX Fact Tables Dimension Tables defined. 8 5/4/2018 ABI cube Measure Groups (Measures) Dimensions (Attributes) Date A multi-dimensional data structure. Compressed. Relationships between tables/objects already Cube [Sales Amount] Product Indexes Aggregations Customer

9 SQL Server Connection Server Database Tables 9 5/4/2018 ABI cube

10 SSAS Server MD Connection AdevntureWorksDW2012Multidimensional Server Database Cube Measure Groups Dimensions 10 5/4/2018 ABI cube

11 Storage Mode: Where does data live? Metadata Data Aggregations Metadata Aggregations Metadata MOLAP HOLAP ROLAP MOLAP: Data pulled in during processing time

12 Why is SSAS fast? Compression Indexes Aggregations Uses attribute relationships to answer queries City Sales Jacksonville 1,000,000 Atlanta 2,000,000 Savannah 500,000 State Sales FL 1,000,000 GA 2,500, /4/2018 ABI cube

13 SSAS MD Query Processing Query Formula Engine Data Set 1 Data Set 2 FE Cache Data Set 3 Frequently accessed calculations Dimensions Disk Storage Engine Aggregation Data Measure Group Data SE Cache Frequently accessed Subcubes

14 SSAS Tabular Data Model Model DAX/MDX Fact Tables Dimension Tables Tables Tables Date Product Customer Relationships between tables/objects already defined. DAX to define calculations. DAX/MDX to query. Data & Other structures: Dictionaries 14 5/4/2018 ABI cube

15 SSAS Server Tabular AdevntureWorks Server Database Tables 15 5/4/2018 ABI cube

16 Storage Mode: Where does data live? In Memory (VertiPaq) Data In SSAS Columnar No DAX restrictions Calculated tables allowed One data source Partitions allowed Direct Query Data In SQL Server SQL Server choice Some functions optimized, some only allowed in measures Calculated tables not allowed Multiple data sources One partition only (plus sample)

17 SSAS Tabular Query Processing Query Formula Engine FE Cache Data Set 1 Data Set 2 Data Set 3 Frequently accessed calculations. Materialized data sets. Only for MDX queries. Direct Query Storage Engine VertiPaq (Compressed In-Memory) SE Cache Uncompressed frequently accessed data. pagefile.sys

18 Controlling Memory - Tabular SSAS Setting Default value VertiPaqPagingPolicy 1 VertiPaqMemoryLimit 60 VertiPaqPagingPolicy = 0 VertiPaqPagingPolicy = 1 VertiPaqMemoryLimit: The limit Paging allowed

19 Summary Tabular Mode Query Time Processing Time In Memory DirectQuery Multidimensional Mode MOLAP ROLAP Query Time Processing Time

20 Demo

21 Types of queries Tabular VertiPaq: Select * from Table Partitions: Add where clause DirectQuery: Left Joins. Some DAX functions cannot be translated and have to be resolved in FE. MaxIntermediateRowSize MD Select used columns from fact Table Select Distinct column from dimension table Distinct Counts: Add order by Partitions: Add Where clause

22 Best Practices Use Views to feed the cube/model. Model with subset of data. Use partitioning. Only bring in columns that are needed. Smaller data types Lower cardinality e.g., Timestamp columns

23 Thank you! Questions? Please give feedback! Contact

24 References SSAS General Direct Query Mode MaxIntermediateRowsetSize DAX formula compatibility in DirectQuery mode