The correct answer is that deleting a Singer row will automatically delete all associated Album rows. This is because the `ON DELETE CASCADE` clause on the foreign key from Albums to Singer enforces referential integrity at the database level, ensuring that when a parent row in the interleaved table hierarchy is removed, all child rows referencing it are also removed automatically. On the Google Professional Cloud Database Engineer exam, this concept tests your understanding of Cloud Spanner’s interleaved table relationships and how `ON DELETE CASCADE` behavior differs from standard foreign key constraints in other databases—a common trap is assuming you must manually delete child rows or that cascade only applies to indexed columns. Remember the memory tip: “Cascade cuts the chain—delete the parent, children fall away.”
PCDE Design and implement database schemas Practice Question
This PCDE practice question tests your understanding of design and implement database schemas. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
CREATE TABLE Singers (
SingerId INT64 NOT NULL,
FirstName STRING(1024),
LastName STRING(1024),
SingerInfo BYTES(MAX)
) PRIMARY KEY (SingerId);
CREATE TABLE Albums (
SingerId INT64 NOT NULL,
AlbumId INT64 NOT NULL,
AlbumName STRING(1024)
) PRIMARY KEY (SingerId, AlbumId),
INTERLEAVE IN PARENT Singers ON DELETE CASCADE;
Refer to the exhibit.
Which of the following statements is true regarding this schema design?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Deleting a Singer row will automatically delete all associated Album rows.
Option A is correct because the `ON DELETE CASCADE` clause on the foreign key from `Albums` to `Singer` ensures that when a row in the `Singer` table is deleted, all rows in the `Albums` table that reference that singer are automatically deleted. This is a standard referential integrity behavior in relational databases, and in Cloud Spanner (the technology context for PCDE), it is enforced at the database level to maintain consistency.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Deleting a Singer row will automatically delete all associated Album rows.
Why this is correct
The ON DELETE CASCADE clause enforces this behavior.
Related concept
Read the scenario before looking for a memorised answer.
✗
The Albums table cannot have any secondary indexes because of the INTERLEAVE clause.
Why it's wrong here
Interleaved tables can have secondary indexes; the INTERLEAVE clause does not restrict them.
✗
The Albums table's rows are physically stored independent of the Singer table.
Why it's wrong here
Interleaving co-locates child rows with the parent row for efficient joins.
✗
The Albums table's primary key must include the SingerId column only.
Why it's wrong here
The primary key is (SingerId, AlbumId); SingerId alone is insufficient.
✗
The ON DELETE CASCADE clause ensures that deleting an Album row will delete the corresponding Singer row.
Why it's wrong here
Cascade goes from parent to child, not child to parent.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the direction of `ON DELETE CASCADE` — candidates mistakenly think it deletes the parent when a child is deleted, but it only propagates from parent to child.
Detailed technical explanation
How to think about this question
In Cloud Spanner, interleaved tables use a parent-child relationship where child rows are stored physically interleaved with the parent row, optimizing join performance and reducing read latency. The `ON DELETE CASCADE` option is enforced at the database layer, and if a parent row is deleted, the database automatically deletes all interleaved child rows in the same transaction, ensuring referential integrity without application-level logic. This design is particularly useful for hierarchical data like a singer and their albums, where cascading deletes prevent orphaned records.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Design and implement database schemas — This question tests Design and implement database schemas — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Deleting a Singer row will automatically delete all associated Album rows. — Option A is correct because the `ON DELETE CASCADE` clause on the foreign key from `Albums` to `Singer` ensures that when a row in the `Singer` table is deleted, all rows in the `Albums` table that reference that singer are automatically deleted. This is a standard referential integrity behavior in relational databases, and in Cloud Spanner (the technology context for PCDE), it is enforced at the database level to maintain consistency.
What should I do if I get this PCDE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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