In order for a thing to be considered legacy, there needs to be a widespread successor available.
SQL might have been invented in the 70s but it's still going strong as no real alternative has been widely adopted so far - I'd wager that you will find SQL at most software companies today.
I mean kinda? It's legacy in the "we would never invent this as the solution to the problem domain that's today asked of it."
We would invent the underlying engines for sure but not the language on top of it. It doesn't map at all to how it's actually used by programmers. SQL is the JS to WebAssembly, being able to write the query plan directly via whatever language or mechanism you prefer would be goated.
It has to be my biggest pain point dealing with SQL, having to hint to the optimizer or write meta-SQL to get it to generate the query plan I already know I want dammit! is unbelievably frustrating.
> having to hint to the optimizer or write meta-SQL to get it to generate the query plan I already know I want dammit'
That's not in the domain of SQL. If you're not getting the most optimized query plan, there is something wrong with the DBMS engine or statistics -- SQL, the language, isn't supposed to care about those details.
That's my point, I think we've reached the point where SQL the langage can be more of a hindrance than help because in a lot of cases we're writing directly to the engine but with oven mitts on. If I could build the query from the tree with scan, filter, index scan, cond, merge join as my primitives it would be so nice.
That's the thing though, I still want my data to be relational so NoSQL databases don't fit the bill. I want to interact with a relational database via something other than the SQL language and given that this language already exists (Postgres compiles your SQL into an IR that uses these primitives) I don't think it's a crazy ask.
> It's legacy in the "we would never invent this as the solution to the problem domain that's today asked of it."
I don't think that definition of legacy is useful because so many things which hardly anyone calls "legacy" fit the definition - for example: Javascript as the web standard, cars in cities and bipartisan democracy.
I think many of us would say that that none of these is an ideal solution for the problem being solved, but it's what we are stuck with and I cannot think anyone could call it "legacy systems" until a viable successor is widespread.
