[AWS Certificate]-DynamoDB Partition

DynamoDB Partitions

 

• Store DynamoDB table data (physically)
• Each (physical) partition = 10GB SSD volume
• Not to be confused with table's partition/hash key (which is a logical partition)
• One partition can store items with multiple partition keys
• A table can have multiple partitions
• Number of table partitions depend on its size and provisioned capacity
• Managed internally by DynamoDB
• Provisioned capacity is evenly distributed across table partitions
• Partitions once allocated, cannot be deallocated (important!)

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Calculating DynamoDB Partitions

• 1 Partition = 1000 WCUs or 3000 RCUs (Maximum supported throughput per partition)
• 1 Partition = 10GB of data
• No. of Partitions = Either the number of partitions based on throughput or the number of partitions based on size, whichever is higher

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Partition Behavior Example (Scaling up Capacity)

 

• Provisioned Capacity: 500 RCUs and 500 WCUs

  

• Storage requirement < 10 GB
• Number of Partitions:
         P = (500 RCUs/3000 + 500 WCUs/1000)
         = 0.67 => rounded up => 1 parition
• Say, we scale up the provisioned capacity
• New Capacity: 1000 RCUs and 1000 WCUs
         P = (1000 RCUs/3000 + 1000 WCUs/1000)
         = 1.33 => rounded up => 2 partitions 

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Partition Behavior Example (Scaling up Storage)

 

• Provisioned Capacity = 1000 RCUs and 500 WCUs
• Storage Size = 5GB

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Partition Behavior Example (Scaling up Storage)

• Provisioned Capacity = 1000 RCUs and 500 WCUs
• New Storage size = 50GB

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Partition Behaviro Example (Scaling up Storage)

• Provisioned Capacity = 1000 RCUs and 500 WCUs
• New Storage size = 50GB

 

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Partition Behavior Example (SCaling up Storage)

• Provisioned Capacity = 1000 RCUs and 500 WCUs
• New Storage size = 500GB

 

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DynamoDB Scaling

 

• You can manually scale up provisioned capacity as and when need
• You can only scale down up to 4 times in a day
• Additional one scale down if no scale downs in last 4 hours
• Effectively 9 sclae downs per day
• Scaling affects partition behavior
• Any increase in partitions on scale up will not result in decrease on scale down (Important!)
• Partitions once allocated will not get deallocated later

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Auto Scaling in DynamoDB

 

• No additional costs, uses AWS Application Auto Scaling service
• You set the desired target utilization, minimum and maximum provisioned capacity

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DynamoDB Scaling and Partition Behavior

• Say, we want to migrate a 5GB SQL database to DynamoDB
• Provisioned Capacity needed during BAU is 1000 RCUs and 500 WCUs

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DynamoDB Scaling and Partition Behavior

 

• Say, we want to migrate a 5 GB SQL database to DyanmoDB
• Provisioned Capacity needed during BAU is 1000 RCUs and 500 WCUs
• To speed up the migration, we scale up the write capacity temporarily to 5000 WCUs

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DynamoDB Scaling and Partition Behavior

 

• Say, we want to migrate a 5GB SQL database to DynamoDB
• Provisioned Capacity needed during BAU is 1000 RCUs and 500 WCUs
• To speed up the migration, we scale up the write capacity temporarily to 5000 WCUs

 

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DynamoDB Scaling and Partition Behavior

 

• Say, we want to migrate a 5 GB SQL database to DynamoDB
• Provisioned Capacity needed during BAU is 1000 RCUs and 500 WCUs
• To speed up the migration, we scale up the write capacity temporarily to 5000 WCUs
• Post migration, we scale back to 500 WCUs

 

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DynamoDB Scaling and Partition Behavior

 

• Say, we want to migrate a 5 GB SQL database to DynamoDB
• Provisioned Capacity needed during BAU is 1000 RCUs and 500 WCUs
• To speed up the migration, we scale up the write capacity temporarily to 5000 WCUs
• Post migration, we scale back to 500 WCUs