1. 03 Data Import - Connecting To Data Sources
Chris Webb

2. Agenda
Importing data, live connections and DirectQuery in Power BI Desktop
Power BI Desktop and Power Query
Data sources for importing data in Power BI Desktop
Locale
Authentication
Configurable options
Connecting to data in PowerBI.com

3. Data Sources For Power BI Desktop
Power BI Desktop can connect to data sources in three ways:
You can copy data from a data source and store it inside Power BI’s own native database engine
You can store data externally in SQL Server Analysis Services
Basically the same engine as used in Power BI Desktop
Doing this stops you doing any modelling work in Power BI Desktop
You can create DirectQuery connections to some data sources
You model the data in Power BI but do not import it
Every time you run a query, Power BI generates SQL to get the data it needs

4. Pros/Cons Of Importing Data
Importing data into Power BI is the option you are likely to use most
Benefits:
Fast query performance
All your import, modelling and report design work is in one place
Access to all the latest language and engine improvements
Disadvantages:
Max model size in PowerBI.com is 1GB after compression (250MB from Excel)
Data import can be slow
Data needs to be refreshed to stay up-to-date
Difficult to share import/modelling work between multiple Power BI files

5. Pros/Cons Of Live Connections To SSAS
Benefits:
You can partition tables and only refresh data that has changed
You are only limited by the memory available on your server
Better security options
Takes modelling decisions away from end users
Disadvantages:
Expensive: needs high-spec server, SQL Server Enterprise or BI Edition licence, skilled developers and administrators
Takes time to create a single model
Potential latency issues between Power BI and SSAS server
Latest features only available in SQL Server 2016

6. Pros/Cons Of DirectQuery
Benefits:
Data is always up-to-date, no need to refresh it
No data is stored in Power BI (except for caching)
Allows you to work with the largest data volumes
Disadvantages:
Worst query performance
Tuning your data source will take the most work
Limited data transformation and modelling capabilities
Frequent data changes can be confusing for end users

7. Power BI Desktop And Power Query
The data import experience in Power BI is basically the same as that provided by Power Query in Excel
Differences in Power Query:
The presence of the Excel worksheet as a data source to allow for user interaction
More flexibility in code at the advanced level
Power Query can load data to a table in the worksheet as well as loading data direct to the Excel Data Model

8. Data Sources In Power BI Desktop
Relational databases: SQL Server, Oracle, Access, any ODBC
Azure databases and services
Files: text, csv, XML, JSON, Excel
Web pages and web services
OData feeds
Enter your own data in a freeform grid
Import data using an R language script
Others including SharePoint Lists, SalesForce, Facebook, Exchange Online, Dynamics CRM
Data sources in Preview mode will need to be enabled on the Option dialog

9. Locale
Different locales use different formats for dates, thousands separators and decimal separators
By default Power BI Desktop will assume that data sources use the same locale as your operating system
You can change the locale used in the Data Load tab of the Options dialog
You can also set a locale to use for an individual text or csv file

10. Authentication
Power BI Desktop stores credentials used to connect to data sources in its own data store
Credentials are not stored inside the Power BI file
Therefore if your Power BI file is opened on another PC you may need to re-enter credentials
Credentials can be edited and/or deleted in the Data Source Settings dialog

11. Configurable Options
There are various useful configurable options that can be set on the Options dialog
Turn on/off auto-detection of data types and headers for unstructured sources
Relationships:
Import relationships from data sources that have them
Update relationships when refreshing data
Auto-detect relationships from data when none exist
Allow background loading of data previews (may use lots of memory/CPU for some sources)

12. Data Sources In PowerBI.com
When working in PowerBI.com you have slightly different options for the data sources you can connect to
You can connect to cloud-based databases and services like Azure SQL Database and Azure SQL Data Warehouse with DirectQuery
You can use organisational content packs that your colleagues have created to connect to your organisation’s data sources
You can use content packs for services to connect to third party cloud service providers like Google Analytics, MailChimp and GitHub
You can push data into PowerBI.com programmatically via the API