MongoDB Aggregation Framework: Understanding $match

What is the $match Stage?

$match is an aggregation pipeline stage that filters documents to pass only those that meet the specified condition(s).

It uses the same query syntax as the standard MongoDB find operation, making it familiar to users who have worked with queries.

• Filters documents based on criteria.
• Uses MongoDB query operators like $eq, $gt, $in, etc.
• Reduces the number of documents processed in later pipeline stages.

Syntax and Usage

The $match stage takes a document that specifies the query conditions.

It is typically the first or one of the first stages in an aggregation pipeline to filter data early.

• Basic syntax: { $match: { <query> } }
• Example: { $match: { status: "A" } } filters documents where status equals 'A'.

Example: Using $match in an Aggregation Pipeline

Consider a collection named orders with documents containing fields like status and amount.

We want to filter orders where status is 'A' and amount is greater than 100.