Schema versioning strategies in MongoDB - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is schema versioning in MongoDB?

Schema versioning is a way to manage changes in the structure of documents over time, allowing applications to handle different versions of data smoothly.

beginner

Why is schema versioning important in MongoDB?

Because MongoDB is schema-less, documents can have different shapes. Versioning helps keep track of these changes and ensures the application knows how to read and write data correctly.

beginner

Name one common strategy for schema versioning in MongoDB.

One common strategy is to add a version field inside each document, like "schemaVersion", to indicate which structure the document follows.

intermediate

How does the 'version field' strategy work in practice?

Each document has a field showing its schema version. When reading data, the application checks this field and processes the document according to its version, applying any needed transformations.

intermediate

What is a migration script in schema versioning?

A migration script is a program that updates old documents to the new schema version by changing their structure or adding/removing fields.

What does schema versioning help with in MongoDB?

A Improving query speed automatically

B Enforcing strict data types on all fields

C Managing changes in document structure over time

D Backing up the database daily

Schema versioning helps manage changes in document structure over time so applications can handle different versions.

Which field is commonly added to documents for schema versioning?

A createdAt

B schemaVersion

C userId

D password

The 'schemaVersion' field indicates the version of the document's structure.

What is the main purpose of a migration script?

A To update documents from old schema versions to new ones

B To delete old documents

C To create indexes

D To backup data

Migration scripts update documents to match the new schema version.

MongoDB is called 'schema-less' because:

A It automatically creates schemas

B It does not store any data

C It only supports one schema

D It does not require a fixed document structure

MongoDB allows documents to have different structures, so it is called schema-less.

When reading a document with schema versioning, the application should:

A Check the version field and handle accordingly

B Ignore the version and read as is

C Delete the document if version is old

D Convert all documents to JSON

The application checks the version field to know how to process the document.

Explain what schema versioning is and why it is useful in MongoDB.

Think about how MongoDB documents can change over time.

Describe a common strategy to implement schema versioning in MongoDB and how migration scripts fit in.

Consider how you keep track of document versions and update them.