RDS Queries working slow after schema import and dump

Question

I have a t3.small instance for my database I was inserting records after adding indexes to a table using a script, the script is expected to run around for 18 minutes and insert the records, at the same time I imported another schema which is 1.8 GB my existing schema is 1.3 GB, afterward the queries got slow then I deleted the new imported schema still for whole one day the queries were slow, want to know the reason behind this as t3.small has storage of 20 GB, I checked the metrics for these parameters at that time DiskQueueDepth , BurstBalance was low, BinLogDiskUsage was high. I Want to avoid this in the future as it incurs downtime and timeout for the APIs.

Manish Bhasin · Answer

Hello

T3 instances are the next generation burstable general-purpose instance type that provide a baseline level of CPU performance with the ability to burst CPU usage at any time for as long as required. T3 instances offer a balance of compute, memory, and network resources and are ideal for database workloads with moderate CPU usage that experience temporary spikes in use.

T3 instances accumulate CPU credits when a workload is operating below baseline threshold. Each earned CPU credit provides the T3 instance the opportunity to burst with the performance of a full CPU core for one minute when needed.

Amazon RDS T3 instances are configured for Unlimited mode, which means they can burst beyond the baseline over a 24-hour window for an additional charge.

.When its CPU utilization falls below the baseline, it uses the CPU credits that it earns to pay down the surplus credits that it spent earlier. So in simpler terms, T3 instances can go 'negative' on CPU credits if they need to.

Please see Baseline utilization in following link

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/burstable-credits-baseline-concepts.html

https://repost.aws/questions/QU9NqNOWYMSrCy-xreluy7OQ/is-db-t3-medium-run-in-unlimited-mode

https://repost.aws/questions/QUPIgVWEomSHOaxjtkuPI-hA/ec2-cpu-credit-balance-stuck-at-zero-even-not-spending-any-credit-for-few-hours

[1] Key concepts and definitions for burstable performance instances - https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/burstable-credits-baseline-concepts.html
[2] Unlimited Mode for Burstable Performance Instances - https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/burstable-performance-instances-unlimited-mode.html
[3] Monitoring Your CPU Credits - https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/burstable-performance-instances-monitoring-cpu-credits.html?shortFooter=true

Also , it is good to look at following
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Understanding Burst vs. Baseline Performance with Amazon RDS and GP2

https://aws.amazon.com/blogs/database/understanding-burst-vs-baseline-performance-with-amazon-rds-and-gp2/

RDS Queries working slow after schema import and dump

Also , it is good to look at following

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