- A
pg_stat_replication view on the primary.
Shows replication lag and status.
- B
pg_replication_slots view on the replica.
Why wrong: That view doesn't exist; use pg_stat_replication on replica.
- C
Replica lag metric in Cloud Monitoring.
Provides lag in seconds.
- D
max_wal_size configuration parameter.
Why wrong: Affects WAL retention but doesn't directly diagnose lag.
- E
SHOW REPLICATION STATUS command.
Why wrong: Not a valid PostgreSQL command.
Question 141 of 1,000
PCDOE Design and Plan Database Solutions Practice Question
This PCDOE practice question tests your understanding of design and plan database solutions. 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.
An organization uses Cloud SQL for PostgreSQL with read replicas to offload reporting queries. During peak, the primary instance's CPU spikes to 90%. The team suspects the read replica is falling behind. Which two settings should they check to diagnose replication lag? (Choose TWO.)
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"primary"Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
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
✓
pg_stat_replication view on the primary.
Option A is correct because the `pg_stat_replication` view on the primary instance shows the WAL sender process state, including the `write_lag`, `flush_lag`, and `replay_lag` columns that directly measure replication lag in PostgreSQL. This view provides real-time data on how far behind each standby (including read replicas) is in receiving, flushing, and applying WAL data, making it the primary diagnostic tool for replication lag.
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.
- ✓
pg_stat_replication view on the primary.
Why this is correct
Shows replication lag and status.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
pg_replication_slots view on the replica.
Why it's wrong here
That view doesn't exist; use pg_stat_replication on replica.
- ✓
Replica lag metric in Cloud Monitoring.
Why this is correct
Provides lag in seconds.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
max_wal_size configuration parameter.
Why it's wrong here
Affects WAL retention but doesn't directly diagnose lag.
- ✗
SHOW REPLICATION STATUS command.
Why it's wrong here
Not a valid PostgreSQL command.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between PostgreSQL-specific commands and MySQL commands, so the trap here is that candidates familiar with MySQL might choose `SHOW REPLICATION STATUS` (which is `SHOW REPLICA STATUS` in MySQL 8.0.23+) instead of the correct PostgreSQL diagnostic tools.
Trap categories for this question
Command / output trap
Not a valid PostgreSQL command.
Detailed technical explanation
How to think about this question
Replication lag in PostgreSQL is measured using the `pg_stat_replication` view's `write_lag`, `flush_lag`, and `replay_lag` columns, which represent the time difference between the primary's WAL write and the replica's corresponding action. Cloud SQL for PostgreSQL exposes these metrics via Cloud Monitoring as the `cloudsql.googleapis.com/database/postgresql/replication/replica_lag` metric, which aggregates the `replay_lag` value. In a real-world scenario, high CPU on the primary can cause WAL generation to outpace the replica's apply rate, leading to increasing lag that can be observed in both the view and the metric.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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.
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FAQ
Questions learners often ask
What does this PCDOE question test?
Design and Plan Database Solutions — This question tests Design and Plan Database Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: pg_stat_replication view on the primary. — Option A is correct because the `pg_stat_replication` view on the primary instance shows the WAL sender process state, including the `write_lag`, `flush_lag`, and `replay_lag` columns that directly measure replication lag in PostgreSQL. This view provides real-time data on how far behind each standby (including read replicas) is in receiving, flushing, and applying WAL data, making it the primary diagnostic tool for replication lag.
What should I do if I get this PCDOE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
This PCDOE 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 PCDOE exam.
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