💡 Tip and Trick: MongoDB Polymorphic & Outlier Pattern 💡

August 5, 2024

This content originally appeared on DEV Community and was authored by Danny Chan

Scale:

Cheaper
Flexibility to scale horizontally through sharding
Distributing data across multiple servers
When database exceeds capacity, sharding and split it over two servers

BSON:

Binary representation of JSON (JavaScript Object Notation) documents
Data types: Double, String, Object, Array, Binary Data, ObjectId, Boolean, Date, Null, Regular Expression, JavaScript, 32-bit Integer, Timestamp, 64-bit Integer, Decimal128, Min Key, Max Key

Documents:

Grouped together in collections
16 megabyte size limit
Related collections are grouped together and stored in a database

_id:

Unique for each document in a collection
Immutable
Any type (cannot be array)

Challenge:

Access data together should be stored together
Storage is a small cost, developers are expensive
Instead of optimizing for storage, optimize for developers’ time
Implementing business logic
Optimize data model for developer productivity and query optimization

Validation Option:

Choice of throwing an error or a warning if a validation rule is violated

Embrace Document Diversity:

Not all documents in a collection need to have the same fields

Polymorphic Pattern:

Collections are of similar, but not identical
Grouping documents together based on the queries
Example:

{
    "type": "singles",
    "titles": 167
}
{
    "type": "doubles",
    "titles": 177,
    "tournaments": 233
}

Outlier Pattern:

Solve outlier use case (a document has millions of embedding data)
Add has_extras fields
Create a new document where store other embedding data
Example:

{
    "author": "Ken W. Alger",
    "customers_purchased": ["user00", "user01"]
}
{
   "author": "J.K. Rowling",
   "customers_purchased": ["user00", ..., "user999"],
   "has_extras": "true"
}

Reference:

https://www.mongodb.com/developer/products/mongodb/polymorphic-pattern/
Building with Patterns: The Polymorphic Pattern

https://www.mongodb.com/blog/post/building-with-patterns-the-outlier-pattern
Building With Patterns: The Outlier Pattern

Editor