PDE Storing the Data Practice Question
A financial services firm stores transaction records in a BigQuery table partitioned by transaction_date. Compliance requires that rows older than seven years be permanently and irreversibly deleted, and the team must prove deletion occurred. The table currently uses the default partition expiration of never. The engineer must implement the retention policy without dropping the whole table. (Choose two.)
⚠ Common exam trap
The trap here is treating a scheduled DELETE as equivalent to partition expiration, when time travel and fail-safe retention mean deleted rows are not immediately and irreversibly gone.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Verify retention by querying INFORMATION_SCHEMA.PARTITIONS to confirm partitions beyond the retention window no longer exist.
Partition expiration is the native BigQuery mechanism that irreversibly removes whole partitions once they age past the retention window, and it operates without dropping the table so recent data stays available. The compliance proof comes from INFORMATION_SCHEMA.PARTITIONS, which shows exactly which partitions remain. A scheduled DELETE leaves recoverable copies through time travel and fail-safe, Cloud Storage lifecycle rules cannot see BigQuery-managed storage, and key destruction is not selective enough to age out only old rows.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use Cloud Key Management Service with a customer-managed encryption key and destroy the key version after seven years.
Why it's wrong here
Destroying a key version renders data encrypted with it unreadable, which is a valid cryptographic erasure technique, but BigQuery's default encryption uses Google-managed keys unless customer-managed keys are explicitly configured, and key destruction affects all data using that key, not just rows older than seven years. It cannot selectively age out old partitions while keeping recent data readable.
- ✓
Verify retention by querying INFORMATION_SCHEMA.PARTITIONS to confirm partitions beyond the retention window no longer exist.
Why this is correct
After partition expiration removes old partitions, INFORMATION_SCHEMA.PARTITIONS lists the partitions that remain, giving auditors evidence that partitions past the seven-year boundary are gone. This metadata view is the standard way to demonstrate which partitions exist and their sizes. Combined with partition expiration, it provides the proof of deletion that compliance demands.
- ✗
Configure a Cloud Storage lifecycle rule on the table's underlying data to remove objects older than seven years.
Why it's wrong here
BigQuery manages its own internal storage and does not expose table data as Cloud Storage objects that lifecycle rules can target. Lifecycle rules apply to buckets the customer owns, such as exported files, not to BigQuery-managed columnar storage. Applying such a rule would have no effect on the table and therefore cannot enforce the retention requirement.
- ✗
Create a scheduled query that runs DELETE FROM the table WHERE transaction_date < DATE_SUB(CURRENT_DATE(), INTERVAL 7 YEAR).
Why it's wrong here
A scheduled DELETE removes rows logically but BigQuery time travel retains deleted data for up to seven days and fail-safe storage retains it for an additional period, so the data is not immediately irrecoverable. It also incurs DML costs and consumes slots on large tables. While it can enforce retention, it does not by itself guarantee the irreversible deletion the compliance requirement demands.
- ✓
Set a partition expiration on the table so partitions older than the required retention window are deleted automatically.
Why this is correct
Partition expiration lets BigQuery delete entire partitions once they pass the configured time limit, which for a table partitioned by transaction_date aligns exactly with the seven-year retention requirement. It removes whole partitions without dropping the table, so recent data stays queryable. This is the native, low-maintenance mechanism for time-based retention on partitioned tables and satisfies irreversible deletion of aged records.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Google Cloud exam blueprint
This PDE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PDE exam.