Connecting to and Preparing Data23% of the exam
Saved data sources and multiple connections
What a saved .tds stores (connection information plus calculations, groups, sets, bins and default field properties) versus a packaged .tdsx, how to reuse it from the Connect pane, and how a second connection in one data source enables a cross-database join.
Create live connections and extracts: Create a live connection to a data source; Explain the differences between using live connections versus extracts; Create an extract; Save metadata properties in a .TDS; Create a data source that uses multiple connections.
~8 min read · 7 practice questions ·
What the exam expects
- Save a data source with Add to Saved Data Sources and list what a .tds file stores.
- Choose between a .tds and a packaged .tdsx based on whether everyone can reach the underlying data.
- Reconnect to a saved data source from the Saved Data Sources section of the Connect pane or with File > Open.
- Build a data source with more than one connection and join tables across them, and name the data that can't take part.
- Key terms: .tds (data source file: connection information and metadata, no data); .tdsx (packaged data source: the .tds plus a copy of local file data or extracts); metadata (calculated fields, groups, sets, bins, renamed fields and default properties layered on the data); multi-connection data source (one data source holding connections to more than one database or file); cross-database join (a join between tables from different connections).
Key facts
.tds contents
- Detail
- Data source type, connection information, groups, sets, calcs, bins, default field properties
.tds holds data?
- Detail
- No; only what is needed to connect plus metadata
.tdsx adds
- Detail
- A copy of local file-based data or extracts, in one zipped file
Save command
- Detail
- Right-click the data source in the Data pane > Add to Saved Data Sources
Default save folder
- Detail
- Datasources folder of the Tableau repository
Reconnect
- Detail
- Saved data sources section of the Connect pane, or File > Open
Add a connection
- Detail
- Add next to Connections in the Data Source page left pane
Multi-connection on a sheet
- Detail
- Functions as one combined data source
Connection colors
- Detail
- Tables in the canvas and columns in the grid are colored by connection
Can't cross-database join
- Detail
- Cube data, most extract-only data, published Tableau data sources
- Why does a .tds still need the original file or database to show any data?
- When does Tableau prompt you to locate or replace data after opening a .tds?
- Why do rows with null join keys drop out of a join after you add a second connection?
- Why can't you union a table from one connection with a table from another?
- What does a missing connector in the Add list tell you?
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