Database Index
intermediateDefinition
A lookup list a database keeps for one column, like the index at the back of a book, so it can find matching rows without reading the whole table.
In the wild
Searching a million orders by email takes seconds until the email column gets an index; then the same search comes back almost instantly.
More from Backend & APIs
API (Application Programming Interface)
A set of agreed requests one program can send to another to get data or have something done, like ordering from a restaurant menu without seeing the kitchen.
Authentication vs Authorization
Authentication checks who you are (usually when you log in), and authorization checks what you're allowed to do once the app knows who you are.
Backend
The part of an app that runs on a server, out of sight: it stores the data and does the work behind what you see on the screen.
Connection Pool
A small set of open database connections an app keeps ready and shares between requests, instead of opening a new one every time.
CORS (Cross-Origin Resource Sharing)
A browser safety rule that stops a web page from reading data from a different website unless that other website says it's allowed.
CRUD (Create, Read, Update, Delete)
The four basic things an app does with saved information: add a new item, look at it, change it, and remove it.