MariaDB Uuid as Primary Key Performance Problem / Tweaks

Question

im upgrading our mariadb database from PRIMARY KEY INT AUTO_INCREMENT to UUID PRIMARY KEY. We have around 80 tables with multiple relations between them. I've build a migration script to change the id field to BINARY(16) and created for every row a Uuid v4. Then i've updated the relations with the new uuid (also as BINARY(16)). When i run multiple queries to do a performance benchmark, i have an average performance decrease from 15% on my local docker environment. The id field is a PRIMARY KEY. The relation fields are marked as index and have Foreign Key constraints.

What can i do to improve the performance?

Most of the tables has round about 200k entries. The whole database has a size of 3.2GB

Answer 1

UUIDs are not nice when it comes to performance. In particular, there is no relationship between the 'next' row you fetch via a UUID and all the other rows that are currently cached.

Docker possibly has a "small" value for innodb_buffer_pool_size, thereby leading to I/O when random accesses into the table happen.

UUID v1 can have its bits shuffled to make them "chronological", would remove most of the "randomness" of accesses. But you are using v4.

Plan A: Abandon UUIDs.

Plan B: Use UUID v1 and shuffle the bits

Plan C: Give docker enough room to have a big buffer_pool so that most of the indexes can be kept in RAM.

More: http://mysql.rjweb.org/doc.php/uuid