Data Connections and Preparation Flashcards
7 cards from real Tableau practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Data Connections and Preparation flashcards as text
In Tableau, what is a 'cross-database join' and when would you use it?
Answer: A join that combines tables from two different data sources of different types
A cross-database join lets you combine tables from entirely different data source types (e.g., SQL Server and Excel) in a single data connection.
Which of the following best describes a 'physical table' in Tableau's data model?
Answer: An actual table or query that contributes data at the join/union layer
Physical tables are real tables (or custom SQL queries) that exist at the lower join layer of Tableau's logical data model, where joins and unions are defined.
When using custom SQL in Tableau, what is one important performance consideration?
Answer: Custom SQL bypasses Tableau's query optimization and can result in slower performance
Custom SQL is sent as a subquery to the database, which may prevent the database's query optimizer from applying its full optimizations, potentially slowing performance.
What does the 'Assume Referential Integrity' option in a Tableau join do?
Answer: Tells Tableau to skip checking for unmatched rows, potentially improving performance
'Assume Referential Integrity' instructs Tableau to trust that all join keys match, skipping extra filtering and potentially generating more efficient SQL queries.
Which file format does Tableau use when saving a data extract?
Answer: .hyper
Tableau uses the .hyper file format (introduced in Tableau 10.5) for data extracts, replacing the older .tde format.
When you add a second data source to a Tableau workbook and link it via data blending, what field acts as the linking key?
Answer: A field with the same name that is used in the view from the primary source
Data blending automatically uses fields with matching names between the primary and secondary source as the linking key when those fields appear in the view.
A Tableau user is connecting to a large SQL database and wants to limit initial data load for testing purposes. Which option best achieves this?
Answer: Use extract filters or sampling options during extract creation
When creating an extract, Tableau allows you to apply extract filters and set sampling (top N rows or random sample) to limit how much data is loaded.