Learn the IT-English vocabulary of read replicas: read/write splitting, replication lag, eventual consistency and failover.
0 / 14 completed
1 / 14
A 'read replica' is added to scale a database. What does it handle?
Read replicas serve read traffic so the primary can focus on writes, improving read scalability.
2 / 14
The team implements 'read/write splitting'. What does that mean?
Read/write splitting sends writes to the primary and distributes reads across replicas.
3 / 14
A user sees stale data due to 'replication lag'. What is it?
Replication lag is the time it takes for a write on the primary to propagate to replicas.
4 / 14
Because of lag, replicas offer 'eventual consistency'. What does that mean?
Eventual consistency means replicas catch up eventually, though a read right after a write may be stale.
5 / 14
Which sentence correctly uses 'failover'?
Failover promotes a replica to primary when the original primary becomes unavailable.
6 / 14
Reviewer: 'The read replica's lag is impacting our user-facing dashboard. It's showing old inventory levels for products that have been updated in the primary database.
You need to explain this situation to the team and propose a solution. Choose the most appropriate response to include in the PR description.
This question tests understanding of a common issue with read replicas and how to address it. Option 2 correctly identifies that frequent syncing is not the solution; simply increasing processing power won't fix the fundamental problem of replication lag. The best approach involves acknowledging the expected lag, and proposing a strategic mitigation – in this case, caching – alongside investigating potential configuration issues on the replica itself. Options A and D are technically misdirected; more powerful hardware doesn't address asynchronous data updates, and upgrading the primary is an expensive, often unnecessary, solution.
7 / 14
Reviewer: 'The read replica's lag is impacting our user-facing dashboard. It's showing old inventory levels for products that have been updated in the primary database.
You need to explain this situation to the team and propose a solution. Choose the most appropriate response to include in the PR description.
This question tests understanding of a common issue with read replicas and how to address it. Option 2 correctly identifies that frequent syncing is not the solution; simply increasing processing power won't fix the fundamental problem of replication lag. The best approach involves acknowledging the expected lag, and proposing a strategic mitigation – in this case, caching – alongside investigating potential configuration issues on the replica itself. Options A and D are technically misdirected; more powerful hardware doesn't address asynchronous data updates, and upgrading the primary is an expensive, often unnecessary, solution.
8 / 14
Reviewer: 'The read replica's lag is impacting our user-facing dashboard. It's showing old inventory levels for products that have been updated in the primary database.
You need to explain this situation to the team and propose a solution. Choose the most appropriate response to include in the PR description.
This question tests understanding of a common issue with read replicas and how to address it. Option 2 correctly identifies that frequent syncing is not the solution; simply increasing processing power won't fix the fundamental problem of replication lag. The best approach involves acknowledging the expected lag, and proposing a strategic mitigation – in this case, caching – alongside investigating potential configuration issues on the replica itself. Options A and D are technically misdirected; more powerful hardware doesn't address asynchronous data updates, and upgrading the primary is an expensive, often unnecessary, solution.
9 / 14
Reviewer: 'The read replica's lag is impacting our user-facing dashboard. It's showing old inventory levels for products that have been updated in the primary database.
You need to explain this situation to the team and propose a solution. Choose the most appropriate response to include in the PR description.
This question tests understanding of a common issue with read replicas and how to address it. Option 2 correctly identifies that frequent syncing is not the solution; simply increasing processing power won't fix the fundamental problem of replication lag. The best approach involves acknowledging the expected lag, and proposing a strategic mitigation – in this case, caching – alongside investigating potential configuration issues on the replica itself. Options A and D are technically misdirected; more powerful hardware doesn't address asynchronous data updates, and upgrading the primary is an expensive, often unnecessary, solution.
10 / 14
During a standup meeting, the database team mentions that our read replica is experiencing significant lag. This means that changes made to the primary database aren't immediately reflected on the replica, potentially causing delays for users accessing data through it. Which of the following best describes the *immediate* impact of this lag?
Read replica lag refers to the delay between updates on the primary database and their reflection on the read replica. Option B is correct - users accessing data through the replica will see delayed updates. Options A and D are incorrect because a partial outage or manual restart wouldn't directly explain the observed delay. Option C is fundamentally wrong; replication isn't instantaneous.
11 / 14
You're reviewing a PR that introduces a new feature for caching product data on the read replica. The commit message includes the line: 'Implemented asynchronous replication to minimize latency'. What is the *primary* benefit of this approach?
Asynchronous replication is key here. It doesn't guarantee immediate synchronization (Option A), nor does it directly increase request volume (Option B). Instead, asynchronous replication minimizes the delay in data propagation, which directly improves responsiveness for users accessing the read replica – this aligns with Option C.
12 / 14
A senior developer sends you a Slack message: 'The replication lag is creeping up again. We're seeing delays of over 5 minutes between primary and replica updates. What's the first thing we should investigate to understand why this is happening?'
Replication lag is directly caused by issues within the replication configuration. While network bandwidth (Option A) and user load (Option D) can *contribute* to delays, the root cause identified in the message is the replication process itself – its settings or status. Option B targets this directly.
13 / 14
You're documenting a change related to read replica scaling. Which of the following statements *best* describes the trade-off involved in using eventual consistency with a read replica?
Eventual consistency means that there will be a delay before changes made to the primary database are reflected on the read replica. Option B accurately captures this trade-off – speed is prioritized over immediate accuracy, acknowledging temporary inconsistencies. Options A and C are incorrect as eventual consistency does *not* guarantee immediate accuracy or eliminate conflict resolution.
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A developer writes the following PR description: 'Implemented a new mechanism to automatically failover to the read replica in case of primary database downtime. This ensures continued availability and minimal impact on user experience.' What is the *primary* purpose of this described action?
Failover is about redundancy and graceful degradation. The goal isn't to reduce latency or eliminate data inconsistency (Options A & B) but rather to provide a backup system that can take over if the primary fails, ensuring continued availability – this aligns with Option C.
What does the "Read Replica Scaling" exercise practise?
Learn the IT-English vocabulary of read replicas: read/write splitting, replication lag, eventual consistency and failover.
How many questions are in this exercise?
This exercise has 14 questions, each multiple-choice with a full explanation shown after you answer.
What English level is this exercise for?
This exercise is tagged Intermediate. If the vocabulary feels difficult, browse the Database Optimization category page for an easier module to start with.
Is this exercise free to use?
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Do I get feedback if I answer incorrectly?
Yes — whichever option you choose, right or wrong, you'll immediately see an explanation clarifying the correct term and why the other options don't fit.
Can I retry this exercise?
Yes — once you finish all the questions, a "Try again" button on the results screen resets the exercise so you can practise as many times as you like.
Do I need an account to track my progress?
No account is required. Your progress bar and score for this session are tracked in the browser as you go, but nothing is saved once you leave the page.
Is "Read Replica Scaling" part of a larger series?
Yes — it's one exercise in the Database Optimization category on CoderSlingo. See the category page for the full list of related exercises on similar terminology.
Can I link directly to this exercise?
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Where can I find more exercises like this one?
See the Database Optimization category page for related exercises, or browse the main Exercises hub for other IT English topics.