Unknown Collation Errors in MySQL

More often than not, when importing a new SQL dump into your database, an annoying error pops up: #1273 - Unknown collation: 'utf8mb4_0900_ai_ci'. The fix is usually straightforward—change the collation to one your database supports and move on. But have you ever stopped to wonder what collation actually means under the hood?

What is Collation?

Collation is a set of rules that determines how text is compared and sorted in a database. It defines things like:

1.Whether comparisons are case-sensitive (A vs a)

2. Whether accents matter (é vs e)

3. The order in which characters are sorted

What’s Really Happening Behind the Scenes?

For a deeper understanding, consider this sample SQL statement:

When you execute this query under older collation rules like utf8mb4_general_ci, the database doesn’t just do a simple byte-by-byte comparison. Instead, it follows a more detailed process: