The Chasm and Fan Trap — Learn free

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Questions 1–10 of 10

1. What do Chasm and Fan Traps lead to?
Question 1A. Faster queriesB. Cartesian DataC. Higher cardinalityD. Better normalisationE. Smaller tables
2. How is a Fan Trap defined?
Question 2A. A model with a 'Many to One' relationship in more than two tables joined in one queryB. A model that ends up having a 'One to Many' relationship chained across more than two tablesC. A table with no primary keyD. A query that uses UNION ALLE. A missing foreign key
3. In the Fan Trap example, what is the problem with adding Order Id as a foreign key in the Order Products table?
Question 3A. It makes the Orders table too largeB. It removes the relationship between Customer and OrderC. It prevents customers from placing ordersD. It causes low cardinality in Order Products and duplication of Product, when Product ID should be uniqueE. It requires a UNION ALL
4. What is the suggested solution to the Fan Trap in the Customer, Order and Product example?
Question 4A. Delete the Products tableB. Merge Orders and Products into one tableC. Write two separate queriesD. Add Customer ID to the Products tableE. Have Product ID from the Order Products table as the foreign key in the Orders table, since one Product can have many Orders
5. How is a Chasm Trap defined?
Question 5A. A model with 'Many to One' relationships in more than two tables that are joined in one queryB. A physical model with duplicate primary keysC. A table without a foreign keyD. A star schema with too many dimensionsE. A missing index on a fact table
6. In a Chasm Trap, where does the issue lie?
Question 6A. In the data modelB. In the hardwareC. In the data typesD. In the primary key definitionsE. In the way the query is written, not the data model
7. In the John example from I Am Datapedia!, how many rows result from joining Employee, Target and Sales in one query, and what total is shown?
Question 7A. 12 rows and USD 100kB. 10 rows and USD 100kC. 20 rows and USD 200kD. 2 rows and USD 3ME. 22 rows and USD 220k
8. Which two approaches are given to handle the Chasm Trap?
Question 8A. Add an index or drop the Target tableB. Denormalise the tables or delete duplicatesC. Use an OUTER JOIN or a CROSS JOIND. Write two queries separately, or write two queries within one query using UNION ALLE. Add a surrogate key or a composite key
9. How many rows does the UNION ALL solution produce in the John example?
Question 9A. 2B. 10C. 12D. 20E. 22
10. Which rule about transactional and master tables must one not forget when modelling?
Question 10A. Transactional tables should be 'Many' and master/reference tables 'One'B. Transactional tables should be 'One' and master tables 'Many'C. Both should always be 'Many'D. Both should always be 'One'E. Master tables should have no keys