This is excellent. In the past when replicating via Debezium from a system making heavy use of cascade deletes I’ve had to write a layer that infers these deletes by introspecting the database schema, building a graph of all cascades (sometimes several layers) and identifying rows that should have corresponding delete records. These can then be excluded in whatever downstream system via an anti-join. It works but it will be better to not have to do that and instead have first class support for cascades.
One of the main reasons I use Postgres is I've rarely(never?) seen an article like this posted about it. Every time I've touched MySQL I've found a new footgun.
MySQL is the PHP of databases. It was free, easy to setup and had the spotlight at the right time. The bad decisions that are baked into MySQL are plenty and really sad (like the botched utf8 defaults, the myisam storage engine, strange stuff around replication and mucu more)
It still blows my mind that they called that crappy partial buggy characterset “utf8”. Then later came out with actual utf8 and called it “utf8mb4”. Makes no sense
They should have addressed it much earlier, but it makes way more sense in historical context: when MySQL added utf8 support in early 2003, the utf8 standard originally permitted up to 6 bytes per char at that time. This had excessive storage implications, and emoji weren't in widespread use at all at the time. 3 bytes were sufficient to store the majority of chars in use at that time, so that's what they went with.
And once they made that choice, there was no easy fix that was also backwards-compatible. MySQL avoids breaking binary data compatibility across upgrades: aside from a few special cases like fractional time support, an upgrade doesn't require rebuilding any of your tables.
Your explanation makes it sound like an incredibly stupid decision. I imagine what you're getting at is that 3 bytes were/are sufficient for the basic multilingual plane, which is incidentally also what can be represented in a single utf-16 byte pair. So they imposed the same limitation as utf-16 had on utf-8. This would have seemed logical in a world where utf-16 was the default and utf-8 was some annoying exception they had to get out of the way.
OK, but that makes perfect sense given utf-16 was actually quite widespread in 2003! For example, Windows APIs, MS SQL Server, JavaScript (off the top of my head)... these all still primarily use utf-16 today even. And MySQL also supports utf-16 among many other charsets.
There wasn't a clear winner in utf-8 at the time, especially given its 6-byte-max representation back then. Memory and storage were a lot more limited.
And yes while 6 bytes was the maximum, a bunch of critical paths (e.g. sorting logic) in old MySQL required allocating a worst-case buffer size, so this would have been prohibitively expensive.
The performance impact depends substantially on whether you've configured it to fsync the binlog on every group commit.
Also, it's important to consider that replication and backups serve different purposes. Backups alone are insufficient for high availability, change data capture, point-in-time recovery / undoing a bad change, etc.
Turning it off cause you're not using it seems reasonable, but I'm surprised it has a big effect on performance. Sequential appends to a file are pretty easy as long as you're not doing so many writes per second that there's contention on the write.
I've used bin log for almost decades and never experienced a big performance impact. This even holds for write heavy MySQL instances in ancient times where servers had spinning disks.
And once they made that choice, there was no easy fix that was also backwards-compatible. MySQL avoids breaking binary data compatibility across upgrades: aside from a few special cases like fractional time support, an upgrade doesn't require rebuilding any of your tables.
There wasn't a clear winner in utf-8 at the time, especially given its 6-byte-max representation back then. Memory and storage were a lot more limited.
And yes while 6 bytes was the maximum, a bunch of critical paths (e.g. sorting logic) in old MySQL required allocating a worst-case buffer size, so this would have been prohibitively expensive.
Also, it's important to consider that replication and backups serve different purposes. Backups alone are insufficient for high availability, change data capture, point-in-time recovery / undoing a bad change, etc.