Tableau Data Connections and Preparation 3

Question 1

In Tableau, what is a 'cross-database join' and when would you use it?

Accepted Answer

A join that combines tables from two different data sources of different types

Answer

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.

Question 2

Which of the following best describes a 'physical table' in Tableau's data model?

Accepted Answer

An actual table or query that contributes data at the join/union layer

Answer

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.

Question 3

When using custom SQL in Tableau, what is one important performance consideration?

Accepted Answer

Custom SQL bypasses Tableau's query optimization and can result in slower performance

Answer

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.

Question 4

What does the 'Assume Referential Integrity' option in a Tableau join do?

Accepted Answer

Tells Tableau to skip checking for unmatched rows, potentially improving performance

Answer

'Assume Referential Integrity' instructs Tableau to trust that all join keys match, skipping extra filtering and potentially generating more efficient SQL queries.

Question 5

Which file format does Tableau use when saving a data extract?

Accepted Answer

.hyper

Answer

Tableau uses the .hyper file format (introduced in Tableau 10.5) for data extracts, replacing the older .tde format.

Tableau Practice Test

Tableau Practice Test

Tableau Data Connections and Preparation 3