APM Key Concepts

APM provides performance metrics by collecting timing and metadata for a process from start to finish. There are two key types of data collected: transactions and spans.

Transactions

Transactions represents the entire process from start to finish. For example when measuring an HTTP request, the transaction would represent all timing and metadata for the request from the time the app receives the request to the time a response is sent. All global metadata such as hostname, environment, etc is attached at the transaction level.

Spans

Spans are individual operations that may occur during a transaction. A transaction may have 0 or more spans. For example, a span might measure the time it takes to make a database call within the parent HTTP request transaction.

Example

Looking at the example below, the top line labeled PUT /api/users/:id would be the transaction (an HTTP request), and the subsequent 3 lines would be spans that occured during the transaction.