For Amazon S3 request rates, what's the difference between prefixes and nested folders? How many prefixes can I have in an S3 bucket?

Resolution

Prefixes

A key prefix is a string of characters that can be the complete path in front of the object name. This includes the bucket name. For example, if an object (123.txt) is stored as BucketName/Project/WordFiles/123.txt, then the prefix might be BucketName/Project/WordFiles/123.txt. The prefix can be any length, such as the entire object key name.

If the 123.txt file is in a bucket without a specified path, then Amazon S3 automatically adjusts the prefix value according to the request rate. Partitions can automatically form at any point in the prefix string.

A partitioned prefix in a bucket can support 3,500 PUT/COPY/POST/DELETE or 5,500 GET/HEAD requests per second. There's no limit to the number of prefixes that you can have in a bucket. However, a spike in the request rate might cause throttling.

Note: In Amazon S3, there are no partitions for keys or objects. Partitions exist only at the prefix level, and not at the object level. For more information about how to use prefixes in Amazon S3, see Organizing objects using prefixes.

Folders

When you create a folder in Amazon S3, the service creates a 0-byte object with a key that's set to the provided folder name.

In Amazon S3, a folder groups objects and organizes files. Unlike a traditional file system, Amazon S3 doesn't use hierarchy to organize its objects and files. The Amazon S3 console supports the folder concept only as a way to group and display objects.

A folder is the value between the two slash (/) characters. For example, you store a file as BucketName/Project/WordFiles/123.txt. In this file path, there's a folder, Project, and subfolder, WordFiles. Both Project and WordFiles are folders. If you save the 123.txt file in a bucket without a specified path, then Amazon S3 doesn't use folders to store the file.

Note: The folder structure might not indicate any partitioned prefixes that support request rates.

Difference between prefixes and folders

The difference between a prefix and a folder is the significance of the slash character. For folders, this character signifies a subfolder or object name. For prefixes, a slash is simply a character and doesn't indicate a partition placement.

Note: The folder structure applies only to the Amazon S3 console. For more information, see Organizing objects in the Amazon S3 console by using folders.

Related information

AWS re:Invent 2018: Best practices for Amazon S3 and Amazon S3 Glacier

Organizing, listing, and working with your objects