Exam AWS Certified Database - Specialty topic 1 question 81 discussion

Exam question from Amazon's AWS Certified Database - Specialty

Question #: 81
Topic #: 1

[All AWS Certified Database - Specialty Questions]

A Database Specialist must create a read replica to isolate read-only queries for an Amazon RDS for MySQL DB instance. Immediately after creating the read replica, users that query it report slow response times.
What could be causing these slow response times?

A. New volumes created from snapshots load lazily in the background
B. Long-running statements on the master
C. Insufficient resources on the master
D. Overload of a single replication thread by excessive writes on the master

Show Suggested Answer

Suggested Answer: A 🗳️

by pan24 at July 21, 2020, 10:26 a.m.

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Comments

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pan24

Highly Voted 3 years, 9 months ago

ANS: A snapshot is lazy loaded If the volume is accessed where the data is not loaded, the application accessing the volume encounters a higher latency than normal while the data gets loaded

upvoted 15 times

gelsm

3 years, 8 months ago

https://aws.amazon.com/about-aws/whats-new/2019/11/amazon-ebs-fast-snapshot-restore-eliminates-need-for-prewarming-data-into-volumes-created-snapshots/

upvoted 1 times

hariti_crafting

3 years ago

question is about RDS this link is irrevalent not need to confuse ebs and rds

upvoted 4 times

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RotterDam

Highly Voted 3 years, 4 months ago

Selected Answer: A

Unlike Aurora - RDS does not have a warm pool of cache (unless its POSTGRES and you are using CCM there - but there is MYSQL). First touch penalty. Can be mitigated with doing a select * from all tables

upvoted 10 times

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aviathor

Most Recent 2 years, 1 month ago

Selected Answer: B

An active, long-running transaction can slow the process of creating the read replica. We recommend that you wait for long-running transactions to complete before creating a read replica. If you create multiple read replicas in parallel from the same source DB instance, Amazon RDS takes only one snapshot at the start of the first create action. https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_ReadRepl.html#USER_ReadRepl.Create

upvoted 2 times

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Rayls2000

2 years, 12 months ago

Ans: B https://aws.amazon.com/premiumsupport/knowledge-center/rds-mysql-high-replica-lag/ If the replica SQL_THREAD is the source of replication delays, then those delays could be caused by the following: Long-running queries on the primary DB instance Insufficient DB instance class size or storage Parallel queries run on the primary DB instance Binary logs synced to the disk on the replica DB instance Binlog_format on the replica is set to ROW Replica creation lag

upvoted 2 times

ray6li

2 years, 11 months ago

Correction: Ans: A. Lag != slow response time.

upvoted 3 times

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novice_expert

3 years, 2 months ago

Selected Answer: A

https://aws.amazon.com/about-aws/whats-new/2019/11/amazon-ebs-fast-snapshot-restore-eliminates-need-for-prewarming-data-into-volumes-created-snapshots/

upvoted 3 times