Improve UUID performance by storing the value as binary format in the database instead of string

Problem/Motivation

For now, Drupal stores the UUID values in the entity tables just as plain strings in the database: varchar(128).

This type of storage leads to significant performance issues, compared to the binary UUID format:

Storing UUIDs as strings instead of binary in MySQL results in a 55% storage penalty and significantly degrades performance due to index fragmentation. A string UUID occupies 36 bytes compared to 16 bytes for binary, which reduces buffer pool efficiency, increases disk I/O during reads, and forces expensive, non-sequential "index thrashing" during writes. Furthermore, binary comparisons are computationally cheaper than character-based collation checks, making joins and lookups consistently faster when using the compact BINARY(16) format.

So, switching to the binary format should significantly improve the performance, here are some estimations:

Storage: A 55–70% reduction in storage for the UUID column itself. Because MySQL InnoDB secondary indexes also include the primary key, this space-saving is compounded across every index on your table.

Write Speed (Insert): Up to a 3x–5x faster insertion rate once your dataset exceeds the size of your RAM (Buffer Pool).

Read Speed (Select/Join): Joins and lookups typically see a 20–60% speed improvement because the database compares raw 128-bit numbers instead of performing character-by-character lexical collation checks.

Proposed resolution

To improve the overall performance of Drupal, we should find a way to store UUIDs as binary.

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet