DynamoDB突发容量和自适应扩展 [英] DynamoDB Burst Capacity and Adaptive Scaling
问题描述
我正在查看AWS 博客，然后从 AWS re：发明视频，以了解DynamoDB的自适应缩放和突发的概念。我了解WCU和RCU的概念以及爆破桶堆积300秒的想法，并且分区的WCU / RCU的峰值为1000/3000。
视频的开始时间23:00：
（1）视频提供了一个示例表，该表配备了500个WCU和1500个RCU。该表具有1个分区。 假定不活动5分钟后的突发存储桶将变为500 * 300 = 150K WCU和1500 * 300 = 450K RCU。从那里得出的结论是，现在已经准备好此突发存储桶的这张表可以提供长达5分钟的1K WCU或3K RCU持续性（带有一个分区）
我们如何得出持续1K WCU或3K RCU长达5分钟的数字？ 据我了解，这应该是RCU的计算：450K / 3K = 150秒
（2）在表拆分后，进一步分为两个分区，已配置的WCU / RCU分别在两个分区@ 250/750中平均分配。使用2个分区，峰值RCU翻倍至6K，峰值WCU翻倍至2K，因此他们得出结论：同一突发存储桶现在提供两个分区持续提供100K的持续2K WCU或6K RCU 。 / p>
我们如何得出持续2K WCU或6K RCU长达100秒的数字？ 在我的理解中，这应该是RCU的计算：450K / 6K = 75秒
有任何DynamoDB专家可以帮助得出这个数字吗？
最多持续5分钟的1K WCU或3K RCU
该表仅凭其已配置的容量即可已经承受500 WCU和1500 RCU 。只有超出表的配置容量的使用量才会消耗突发容量。该表可以支持300 W的预配置+ 500 WCU的突发= 1K WCU，持续300秒。
在第二种情况下，问题是相同的。您正在计算450000÷6000，但应计算450000÷（6000-1500）= 100秒，因为突发容量仅以超额速率消耗。
I was going over the AWS blog and from there the AWS re:Invent video to understand DynamoDB's concept of adaptive scaling and bursts. I understand the concept of WCU and RCU and the idea of burst buckets piling up to a period of 300 seconds and that the peak WCU/RCU of a partition is 1000/3000.
Starting time instant 23:00 of the video:
(1) The video gives an example of a table provisioned with 500 WCUs and 1500 RCUs. The table has 1 partition. The burst bucket after 5 minutes of "assumed" inactivity becomes 500*300=150K WCUs and 1500*300= 450K RCUs. And from there it is concluded that this table now with this burst bucket ready can offer up to 5 minutes of sustained 1K WCU or 3K RCU with one partition
How are we arriving at this figure of "up to 5 minutes of sustained 1K WCU or 3K RCU"? In my understanding this should have been the calculation for RCU: 450K/3K=150 seconds
(2) Further down, after the table splits into two partitions with the provisioned WCU/RCU getting evenly divided among the 2 partitions @250/750 respectively. With 2 partitions, the peak RCU doubles to 6K and peak WCU doubles to 2K and therefore they conclude that the same burst bucket now offers up to 100 seconds of sustained 2K WCU or 6K RCU with two partitions.
How are we arriving at this figure of "up to 100 seconds of sustained 2K WCU or 6K RCU"? In my understanding this should have been the calculation for RCU: 450K/6K=75 seconds
Any DynamoDB experts who could help derive this figure?
up to 5 minutes of sustained 1K WCU or 3K RCU
The table can already sustain 500 WCU and 1500 RCU from its provisioned capacity alone. Only usage in excess of the table's provisioned capacity is consuming burst capacity. The table can sustain 500 WCU from provisioned + 500 WCU from burst = 1K WCU, for 300 seconds.
In the second scenario, the issue is the same. You're calculating 450000 ÷ 6000 but should be calculating 450000 ÷ (6000 - 1500) = 100 seconds, because burst capacity is consumed only at the rate of overage.
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