Let us take a closer look at the AWS DynamoDB Partition key with the help of our AWS support Services at Bobcares.

Choosing the Right AWS DynamoDB Partition key

This article covers important factors and strategies to select the right partition key for designing a schema that uses Amazon DynamoDB.

What is a Partition key?

DynamoDB supports two types of primary keys:

• Partition key: A simple primary key composed of one attribute. If the table has only one partition key then no two items can have the same partition value.

• Partition key and sort key: Known as a composite primary key, composed of two attributes: the partition key, and sort key attributes. All data under a partition key will organize by the sort key value.

Needs of partition key:

DynamoDB reserve data as groups of attributes known as items. The Items are the same as rows or records in database systems. Based on the primary key value stored, DynamoDB stores and fetch each item that is unique.

Items distributed across 10-GB storage units called partitions, where each table will be having one or more partitions.

DynamoDB uses the partition key’s value as input to an internal hash function. The output from the hash function determines the partition in which the item stored. Each item’s location determines the hash value of its partition key.

In most cases, all items with the same partition key will store together in a collection as a group of items with the same partition key but different sort keys.

Recommendations for partition keys

Use high-cardinality attributes: These are the attributes that have distinct values for each item, like employee_no, emailid , orderid, customerid, sessionid, and so on.

Use composite attributes: Try to combine more than one attribute to form a unique key that meets your access pattern. Take an example of an orders table with “Customerid#productid#countrycode” as the partition key and “order_date” as the sort key, here the symbol # is to split different fields.

Cache the popular items: when there is a high volume of reading traffic using Amazon DynamoDB Accelerator (DAX). The cache acts as a low pass filter and prevents reads of unusually popular items from swamping partitions. DAX is a fully managed memory cache for DynamoDB.

Add numbers or digits from a predetermined range: Add random numbers or digits for heavy use cases. Suppose you expect a large volume of writes for a partition key with greater than 1000 1 K writes per second. Here you can use an additional prefix or suffix and add them to the partition key.

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Conclusion

To sum up, from the AWS DynamoDB Partition key selecting the right partition key is said to be an important process in the design and building of scalable and valid applications for the top of DynamoDB.