Custom vs. extension attributes in Magento
Video Lesson: Custom vs. extension attributes in Magento
Learn the key differences between custom attributes vs extension attributes in Magento and when to use each for product data.
Published 3 weeks ago
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Lesson Content
Attributes in Magento come in two flavors: custom attributes and extension attributes. Let’s go over each right now, so you understand the differences between the two.
Custom vs extension attributes
Custom attributes are built directly into Magento’s database schema and appear as columns in EAV tables. They're used for data you want to display, filter, or search by in the storefront. These can be created through the admin panel or with database setup scripts.
Extension attributes live outside the core database tables, and are typically connected with an entity ID from a pivot table. Plugins are typically used to integrate the data in this external table with core data queries. They're a lot more advanced to set up, but are perfect for adding complex data structures into existing data queries, or when you need to extend the core (or third-party modules) without modifying core tables.
When to use each attribute type
Custom attributes should be your go-to when you need data that customers will interact with directly.
If you're building something that needs to be searchable or filterable in your storefront, custom attributes are perfect. They work great for simple values like text fields, dropdown options, or yes/no toggles, and they integrate seamlessly with the admin UI.
Extension attributes, on the other hand, shine when you're dealing with complexity.
If you need to store nested data structures or extend a third-party module without touching their code, extension attributes are going to be what you choose. They're also more performance-friendly, since they only load when they are specifically requested, rather than with every data load query.
If you're building integrations with external systems or APIs, extension attributes give you the flexibility you need without compromising your database structure. You can think of custom attributes as part of your data’s core identity, and extension attributes as specialized add-ons that you can attach when needed.
The performance difference becomes especially noticeable at scale — custom attributes add columns to your EAV tables, while extension attributes keep that data separate until you actually need it.
