Document Set Content Types

A document set is a special kind of content type which can be used to group together different  documents with similar metadata as single unit.

Why Document Sets?
You may wonder why go for a document set instead of a folder. Well, behind the scenes, document sets are folders, but they have the ability to include metadata specific to themselves.

Limitations of Folders
For example, inside a document library called "Employee Documents", suppose you need to organize all the relevant documents of each employee like Offer Letters, Resume, Salary Increment Letter etc.

1) No Folder Metadata:  If you create a folder for each Employee and upload the documents inside it, the folder doesn't hold any other information other than the name (which hopefully should be spelled correctly).

2) Inconsistent Metadata
Also, within the folder, you may need additional columns for defining the employee metadata which may be possible through a document content type but the information should be uniform across. User could enter wrong Employee ID or Employee Name metadata for the different documents inside the same folder as highlighted below.

Introducing Document Sets
The above Folder limitations can be resolved using "Document Sets". Lets quickly look how the above scenario and issues are handled by a document set.

As shown below, the Document set is similar to a folder but can hold the metadata for the employee.

Also, all the Document Set metadata information can be shared by all the documents residing inside. Therefore the document metadata remains consistent for all the documents.

Advantages of using Document Sets:

• Welcome Page: Document Set provide an user friendly interface along with a “Welcome Page” for  providing an overview of the contents of the document set. 
• Metadata: Custom metadata/properties can be defined for each document set.
• Shared Metadata: A metadata define for a document set can be further shared by all the documents within it.  The “Document Set Field Synchronization Job”  runs at 15 minutes interval and ensures that the metadata for all the contents within the document set is synchronized with the parent metadata.
• Default Content Types: Default content types can be assigned to Document sets while creating new instances.  A default templates can also be specified for the default content type.
• Available Content Types: The document sets can be configured to have only selected content types. User will only be able to add the content based on the available content types for the document set.
• Workflows: Document sets can have workflows for different events like creating  new document set or  adding new document to it.
• Information Management Policies: Information Management Policies can be easily defined on the document sets. Document set can be archived as a single unit to the record center and content organizer rules can be implemented on the metadata of the document set.The document set is converted into a zip and moved to the specified location using “Send to feature.
• Capture Version History: Document set allows to maintain and capture the version history of the content stored in it on a single location. Folders do not maintain any version history.
• Search: Search Results displays the document sets with a different icon which is easy for end users to identify. Also the documents/ content within the document set can be searched using the search bar given on the welcome page.

Limitations of Document Sets

• Searching ability and performance might degrade as the number of document set increases.
• While downloading documents from document set, the metadata will be lost. 
• Nesting is not possible in Document Sets. Document Set cannot cannot be created inside Document Set
• Document set can be created only for libraries. Lists cannot have document sets but can have folders. 

Points to remembers

• There is no limit on maximum number of documents sets in a document library, but as a best practice, it should not reach 5000 listview threshold limit.
• Document set may have folders in it, but metadata navigation cannot be used.
• There is no limit on total size of a document set. But while using “Send To” feature, if the sum of all documents in the documents cannot exceed 50 MB. For larger work product or number of documents (i.e. more than 50 mb), one should consider Folders.
• In case of shared metadata, if the total number of documents in document set is more than 10, then the job will run every 15 minutes which will update metadata. If the document library has upto 9 documents, the metadata will be updated instantly, without a job.
• Document set maintains the version history, but the end user needs to manually capture the version history of the document set. Whenever a new document is added to the document set, the version of the document set remains unchanged unless version history is manually captured.
• “Content and Structure” option in Site Settings is used to move/ copy the items from one folder/ library/ subsite to another folder/ library/ subsite. But, in case of document sets this functionality does not work as expected. This appears to be a bug.
• Bug in Content and Structure for Document Set: Copying/ moving a “Document Set” from one document library to a specific folder or sub folder in another document library. When we are using OOTB “Content and Structure” feature of SPO, it is moving the selected document set to root of the document library rather than in the selected folder or sub folder. The functionality is working fine for Documents.