Practice Test

True or False: Amazon Redshift provides automatic and manual methods of managing locks.

  • True

Answer: True

Explanation: There are both automatic and manual methods to manage locks in Amazon Redshift. By default, locks are managed automatically but in some cases, manual intervention might be needed.

Which of the following Amazon RDS features are used to manage locks? Select all that apply.

  • A. Amazon RDS Performance Insights
  • B. Amazon RDS Security Groups
  • C. RDS automated backups
  • D. AWS Backup

Answer: A, B

Explanation: Amazon RDS Performance Insights show where DB time is spent, including wait events such as locks. Security Groups also can prevent unauthorized access thus manage locks.

True or False: In Amazon Redshift, locks are automatically released immediately after a transaction is committed.

  • True

Answer: True

Explanation: Amazon Redshift releases the acquired lock immediately after a transaction has been committed.

What type of Amazon RDS events notify a user of an attempt to access locked data?

  • A. Configuration events
  • B. Management events
  • C. Backup events
  • D. Failure events

Answer: D. Failure events

Explanation: A failed attempt to access locked data due to inappropriate permissions or restrictions on the data, will trigger a Failure event in Amazon RDS.

True or False: In Amazon Redshift, shared locks and exclusive locks can coexist on the same table.

  • False

Answer: False

Explanation: In Amazon Redshift, a shared lock preempts obtaining an exclusive lock, and vice versa. Thus, they can’t coexist on the same table.

Which actions lead to an exclusive lock in Amazon Redshift?


Answer: B, D

Explanation: In Redshift, DELETE and UPDATE operations can hold an exclusive lock that preempts other operations on that table.

Is it possible to check what locks are held by a session in Amazon Redshift?

  • A. Yes
  • B. No

Answer: A. Yes

Explanation: It is possible to view what locks are held by a session in Amazon Redshift by querying the STL_LOCKS system view.

True or False: In Amazon RDS, using the Performance Insights feature can help manage locks by visualizing the database load and filter the loads by different dimensions, including SQL, waits, user and host.

  • True

Answer: True

Explanation: AWS RDS Performance Insights provides ways to detect performance problems and help manage locks by providing a visual display of database load, and the ability to filter by different dimensions.

Amazon Redshift uses which kind of lock contention detection methodology?

  • A. Deadlock detection
  • B. Timeout detection
  • C. Both

Answer: A. Deadlock detection

Explanation: Amazon Redshift uses deadlock detection and not timeouts to manage lock contention.

Which RDS feature helps to analyze SQL queries and manage locks effectively?

  • A. Amazon RDS Recommendations
  • B. Amazon RDS Events
  • C. Amazon RDS Performance Insights
  • D. Amazon RDS Manual Snapshots

Answer: C. Amazon RDS Performance Insights

Explanation: Amazon RDS Performance Insights allows you to analyze SQL queries along with waits such as locks. It helps in managing the locks effectively.

True or False: You can manage Amazon Redshift concurrency by managing queues, which also indirectly manages locks.

  • True

Answer: True

Explanation: By managing query queues and concurrency in Redshift, you can manage the data access and reduce lock contention, this indirectly manages the locks.

Interview Questions

What is a deadlock in the context of Amazon RDS?

A deadlock in Amazon RDS occurs when two or more transactions indefinitely wait for each other to release locks.

How does Amazon Redshift manage concurrent write and read operations to prevent data conflicts?

Amazon Redshift uses lock management to ensure the consistency of the data. Write transactions hold exclusive locks. Other transactions can’t modify data until the write transaction releases the lock.

How can you prevent deadlocks in Amazon RDS?

Deadlocks can be prevented in Amazon RDS by designing applications to acquire locks in the same order, minimizing the size of transaction and the duration for which locks are held, and using the READ COMMITTED isolation level.

How are locks automatically managed in Amazon Redshift?

Amazon Redshift manage locks at the system level by automatically acquiring and releasing locks when transactions are initiated or committed, ensuring concurrency and isolation.

Can locks be manually managed in an Amazon RDS MySQL DB instance?

Yes, you can manually manage locks in an Amazon RDS MySQL DB instance by using the LOCK TABLES and UNLOCK TABLES statements.

How does Amazon RDS handle read and write operations simultaneously?

Amazon RDS uses a Multi-AZ deployment where a standby replica in another Availability Zone takes write I/O requests while allowing read I/O to the primary DB instance.

How do you monitor lock activity in Amazon Redshift?

You can monitor lock activity in Amazon Redshift through the system table STL_TR_CONFLICT.

What happens when a session tries to acquire a lock on an Amazon Redshift object that is already locked by another session?

The session attempting to acquire the lock must wait until the session holding the lock releases it.

How does Amazon Redshift handle deadlock situations?

If Amazon Redshift detects a deadlock situation, it automatically terminates one of the sessions and rolls back its transaction.

What Amazon RDS feature can be used to obtain status information about locks?

The SHOW ENGINE INNODB STATUS command can be used in Amazon RDS to obtain status information about InnoDB activity including locks.

How can you view current locks in an Amazon Redshift database?

You can use the STV_LOCKS system view to check the current update, insert, delete and select locks in the Amazon Redshift database.

What happens in Amazon RDS when two conflicting locks are requested on the same row of a table?

In Amazon RDS, if two conflicting locks are requested on the same row of a table, the second lock request will wait for the first to complete before it can be granted.

What is the MVCC in Amazon RDS and how does it help in managing locks?

Multi-Version Concurrency Control (MVCC) in Amazon RDS helps in lock management by creating a new version of a row when it’s updated, allowing other transactions to access the previous version, and thereby reducing lock conflicts.

What is a typical best practice for managing concurrent write operations in Amazon Redshift?

A typical best practice for managing concurrent write operations in Amazon Redshift is to use temporary staging tables for data loading and then switch to the main table once loading is complete.

How do you handle lock conflicts in Amazon Redshift while updating large tables?

In Amazon Redshift, you can handle lock conflicts while updating large tables by using the UPDATE statement with a WHERE clause in separate smaller transactions.

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