> Similarly, yes, functional indices are quite nice if you know how and when to use them.
In fairness to MySQL, you can simulate this surprisingly well by adding indexes to computed columns.
> I’d love to see benchmarks comparing the two RDBMS, properly tuned, with the same workload. I’m OOO this week but I might do that in the future to see for myself.
This is where I see most existing database benchmarks falling down.
tl;dr: testing database performance across engines is a lot harder than most folks realize.
Imagine you have a DB where you're tracking classroom assignments for all public schools in the state. Here are some requirements:
* A classroom must have at least one teacher and at least one student per class scheduled.
* A classroom must not allow more students than its capacity.
* No teacher or student may be assigned to more than one classroom at the same day/time.
To solve this in MySQL, you MUST use application code to check for conflicts and will always be subject to race conditions at your data layer.
The check for existing slots must always be a separate query from the insert, and MySQL cannot restrict overlapping timestamp ranges at the data layer. This requires data custodial work to resolve.
Postgres on the other hand both supports a timestamp range type but also allows exclusion constraints to prevent the same person from being assigned to more than one class when those ranges overlap—a data layer restriction that makes app support code unnecessary and race conditions logically impossible.
Testing "the same workload" is difficult because the data schemas do not match, the application code calling it will not match, and if you did implement it, folks would cry about "apples and oranges" and how they're not the same workload.
In MSSQL, you might write a .NET component that lives in the database and handles the potential race condition. You also might use temporal tables in that engine to track changes over time, something that (again) would involve non-trivial code changes for MySQL and Postgres to match requirements.